Grade+10+Science+-+Optics+Unit

SNC2P: Science, Grade 10, Applied =Unit 4: Physics – Light and Applications of Optics=

Activity 1: Light
[|Overview] | [|Expectations] | **Content** | [|Assignment]

Content
Light is an important form of energy for all of us. Light allows us to see, plants rely on light for photosynthesis, many chemical reactions produce light, and life on Earth would not exist without light. The two types of light sources are luminous and non-luminous. Luminous light can be from natural or artificial sources. Some examples of natural sources of luminous light are the Sun, the Northern Lights, lava from volcanoes, and light produced from fireflies. Various artificial light sources include computer and television screens, a light bulb, and neon signs. Some non-luminous sources of light include mirrors, humans, the moon, books, and houses. ||~ Lava is an example of a luminous light source. Lava can be seen entering the sea at Hawaii Volcanoes National Park. ||
 * **Light**

Light is produced when another form of energy is converted to light energy. One type of light production occurs when steel is heated to temperatures over 2000° C and it emits white light. The heated steel is said to be incandescent. Substances can also be heated to incandescence by electricity. In an incandescent light bulb, electricity passes through a thin filament heating it up and giving off a bright light. Wood, wax, and oil are all forms of chemical energy that can be burned and heated to incandescence. ||
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229670000/SNC2PPU04A01/images/image3.jpeg caption="Image of a woman roasting a hot dog over a campfire. The coals in the fire are an example of heating to incandescence. "]] The burning of wood is a chemical reaction that produces both heat and light energy. || **Ways of Producing Light**

Did you know?

 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229670000/SNC2PPU04A01/images/did_you_know.gif caption="Did you know icon"]] || Did you know that only 5% of the electrical energy that enters an incandescent light bulb is converted to light energy? An incandescent light bulb has a low electrical efficiency with most of the electricity given off as heat energy. These light bulbs become very hot when they are in use. ||


 * Sometimes light is produced when electricity flows through a gas. An example of this is the Aurora Borealis, which is seen in the Northern Hemisphere. Streams of charged particles from the Sun colliding with air molecules in the upper atmosphere around the north pole cause the Aurora Borealis. The Aurora Borealis or Northern Lights, appear as curtains of coloured light in the night sky. ||~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229670000/SNC2PPU04A01/images/image4.jpeg caption="Photograph of green Aurora Borealis."]] ||


 * The lights from neon signs are produced artificially by passing electricity through neon gas within a transparent glass tube. Neon gas produces orange light when electricity is passed through it. Some of the other gases used to produce different coloured lights are sodium vapour that produces yellow light, helium gas that produces white light, and mercury vapour that produces blue-green light. Different gases can be mixed together to produce various types of colours. ||~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229670000/SNC2PPU04A01/images/image5.jpeg caption="Image of a lightning bolt between a cumulonimbus cloud and the ground."]] The light in lightning is produced during a thunderstorm. The air lights up as many electrons crash through the air colliding with molecules. ||

Fluorescent light bulbs use a method of producing light called fluorescence. A fluorescent light tube uses this method of producing light. These light tubes are filled with mercury vapour and the inside surface of the tube is coated with a fluorescent powder. Electricity flowing through the tube produces ultraviolet light that hits the fluorescent coating to produce visible light. ||
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229670000/SNC2PPU04A01/images/image6.jpeg caption="Images show a firefly under a light and then a firefly in the absence of light and emitting a green light."]] The firefly is an organism that produces light by bioluminescence. This method of light production converts chemical energy to light energy in a living organism. || Another way of producing light is called chemiluminescence . The light produced by glow sticks is an example of chemiluminescence. When chemiluminescence takes place in living organisms, it is called bioluminescence.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229670000/SNC2PPU04A01/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > > Answer > > Chemiluminescence is the conversion of ______(c)_____ energy into light energy. > Light is produced in a fluorescent tube by converting _____(d)______ energy into light energy. The fluorescent tube is filled with _____(e)______ vapour. > Answer >
 * 1) ## What is the difference between a luminous and a non-luminous substance?
 * 2) Give an example of a luminous and a non-luminous substance.
 * 1) A substance gives off incandescent heat when it is heated to high ______(a)_______. ______(b)_______ is a method of producing light by converting chemical energy into light energy in a living organism.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229670000/SNC2PPU04A01/images/external_links.gif caption="Resources Icon"]] Resources
Unless otherwise indicated, all images in this activity are from the public domain or are © clipart.com or Microsoft clipart and are used with permission. This is a disclaimer. External Resources will open in a new window. Not responsible for external content.
 * 1) How Stuff Works - Bioluminenscence

=Unit 4: Physics – Light and Applications of Optics=

Activity 2: The Electromagnetic Spectrum
[|Overview] | [|Expectations] | **Content** | [|Assignment]

Content
The electromagnetic spectrum is made up of several types of radiation. Two types of electromagnetic radiation are visible light and radio waves. Electromagnetic radiation is made up of photons. Each type of wave in the electromagnetic spectrum consists of photons with different amounts of energy. For example, the photons in gamma rays have the highest amount of energy and the photons in radio waves have the lowest amount of energy. There are risks involved in exposure to waves in the electromagnetic spectrum with higher energy because these waves can penetrate human tissues and cause damage to cells, mutations, or lead to cancer. The electromagnetic spectrum ====Did you know?====
 * Electromagnetic Spectrum**
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229680000/SNC2PPU04A02/images/did_you_know.gif caption="Did you know icon"]] || Did you know that Sir Isaac Newton was the first person to suggest that the white light from the Sun was made up of a combination of all the colours of the rainbow? White light sources such as the Sun and incandescent light bulbs give off the full spectrum of colours. ||

The part of the electromagnetic spectrum that can be seen by humans is called the visible spectrum. The visible white light of the spectrum is made up of several colours each having a different wavelength and frequency. The different waves in the electromagnetic spectrum can be compared to waves of water. Each type of wave will vary in the distance to the next wave. For example the waves in X rays are very close to each other and therefore X rays have a short wavelength. ||~ A transparent glass prism is shown separating white light into the different colours of the visible spectrum. Water vapour in the atmosphere is able to break up white light to form the colours of the rainbow. || Visible white light can be separated into the various colours of the visible spectrum with a transparent, colourless, glass prism. The visible spectrum is made up of the colours red, orange, yellow, green, blue, indigo, and violet. The colour red has the longest wavelength and the colour violet has the shortest wavelength. Visible light is only a small portion of the electromagnetic spectrum.
 * **Visible Regions of the Electromagnetic Spectrum**

Did you know?

 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229680000/SNC2PPU04A02/images/did_you_know.gif caption="Did you know icon"]] || Did you know that the order of colours in the visible spectrum can be remembered with the mnemonic; **ROY G. BIV** (the name of a fictional person)? Each of the letters of the mnemonic represents one of the colours in the visible spectrum: R – red, O – orange, Y – yellow, G – green, B – blue, I – indigo, and V – violet. ||

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229680000/SNC2PPU04A02/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > Electromagnetic radiation is made up of packages of energy called ______(c)_______. > Answer > > ________(a)_________, ______(b)_________, _________(c)_________, > ________(d)_________, ______(e)_________, _________(f)__________, > and _______(g)_________. Answer > > Answer > > Label the parts of the electromagnetic spectrum > > Answer > Next Humans cannot see the other parts of the electromagnetic spectrum, however, we can use instruments to detect the presence of these invisible regions of the spectrum. The waves with shorter wavelengths such as ultraviolet, X rays, and gamma rays have a higher frequency and a higher energy. The waves with longer wavelengths are radio waves and infrared waves and these waves have a lower frequency and lower energy levels. ||~ In order to prevent counterfeiting some credit cards contain pictures that are only visible with a UV light. || (In order of decreasing wavelength and increasing energy.) This microwave communications tower could be used to transmit information such as telephone calls and Internet access. ||  || Infrared energy can be detected using a special camera. This image shows a man holding a match.Courtesy of NASA ||  ||
 * 1) The electromagnetic spectrum is a set of _______(a)______ that can travel through empty space at the speed of _______(b)_______.
 * 1) List the colours that make up the visible spectrum in order from longest wavelength to shortest wavelength.
 * 1) How is visible white light separated?
 * 1) Label the missing parts of the electromagnetic spectrum.
 * 1) __________________
 * 2) __________________
 * 3) __________________
 * 4) __________________
 * 5) __________________
 * 6) __________________
 * 7) __________________
 * 8) __________________
 * 9) __________________
 * **Invisible Regions of the Electromagnetic Spectrum**
 * Types of Invisible Waves in the Electromagnetic Spectrum**
 * ~ Type of Wave ||~ Description ||
 * Radio waves || * longest wavelength
 * lowest energy level
 * emitted from radio stations, stars, and gases in space ||
 * Microwaves || * used in microwaves to cook food
 * used for radar in weather forecasting
 * used in space by astronomers to learn about the structure of nearby galaxies and our Milky Way ||
 * [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229680000/SNC2PPU04A02/images/image6.jpeg align="center" caption="Image of a communications tower seen above the trees in New Zealand."]]
 * Infrared || * closest to the red waves in the visible spectrum
 * produces heat
 * things that emit infrared radiation include the Sun, the Earth, a fire, humans and other warm blooded animals, and warm cement ||
 * [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229680000/SNC2PPU04A02/images/image7.png align="center" caption="Image of a man shows the warmer areas of the body as a red colour and the cooler areas as a blue colour."]]
 * Ultraviolet (UV) || * the Sun, stars, and other hot objects in space emit UV radiation
 * causes suntans and sunburns ||
 * X rays || * medical uses, e.g. X rays can be used by doctors to view bones and by dentists to look at your teeth ||
 * Gamma rays || * shortest wavelength
 * highest energy level
 * produced by nuclear processes, e.g. nuclear reactions in stars and radioactive material ||

Access the long description of the table

Did you know?

 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229680000/SNC2PPU04A02/images/did_you_know.gif caption="Did you know icon"]] || Did you know that snakes in the viper family such as rattlesnakes use infrared light to detect warm-blooded animals in the dark? Humans cannot see infrared radiation, but snakes have two sensory pits used to image infrared radiation. ||

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229680000/SNC2PPU04A02/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > ||< > ____________________ > ____________________ > ____________________ > ____________________ > ____________________ > ____________________ || > > Answer >
 * 1) State the type of wave in the electromagnetic spectrum that relates to each of the following descriptions:
 * 1) produced by nuclear processes
 * 2) has the longest wavelength
 * 3) used by cell phones
 * 4) can be seen by humans
 * 5) used to view bones
 * 6) causes sunburns
 * 7) produces heat
 * ____________________

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229680000/SNC2PPU04A02/images/external_links.gif caption="Resources Icon"]] Resources

 * 1) The Electromagnetic Spectrum video
 * 2) How Stuff Works - Ultraviolet
 * 3) How Stuff Works - X rays and Gamma rays

=Unit 4: Physics – Light and Applications of Optics=

Activity 3: Transmission, Reflection, and Absorption of Light
[|Overview] | [|Expectations] | **Content** | [|Assignment]

Content
When light strikes an object there are different ways it can be affected. Light can be transmitted, reflected, refracted, and absorbed, depending on the type of matter that it strikes. For example light can transmit or pass through substances such as air, glass, and water. Substances that have the ability to transmit light are called a medium. The amount of transmission will depend on such factors as the thickness, composition, and clarity of the medium. Most of the light is reflected off of substances like mirrors or white snow. However, mirrors reflect light in a predictable pattern; snow scatters light. ||~ The reflection of the mountains surrounding Lake Louise. ||
 * **Transmission, Reflection, and Absorption of Light**

Substances can be classified according to the way they transmit, reflect, and absorb light. The three different types of substances are transparent, translucent , and opaque. Examples of transparent substances are glass, air, plastic wrap, and clean water. [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image4.jpeg caption="Image of a type of butterfly where its body can be seen through the transparent wings. "]] The wings of the butterfly (Greta morgane) are transparent. **Translucent substances will:** Examples of translucent substances are frosted glass, smoke in the air, and human skin. Examples of opaque substances are wood, metal, and rocks. Light travels in all directions from the source of light. Light travels in straight lines until it hits something or passes through a medium with a different composition. A light ray can be drawn to represent a narrow beam of light. When light hits a transparent object, the light rays will pass through the object. Some light rays that strike a translucent object will pass through the object while at the same time other light rays are reflected. Opaque objects will not allow any of the light to pass through, but they will reflect and absorb light rays depending upon their colour. ||~ Light rays can be seen extending in straight lines from behind the cloud. ||
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image3.jpeg caption="Image of a boat riding through the melting sea ice in the ocean."]] Melting sea ice seen in the Arctic results in less light being reflected. || A substance that can absorb a large amount of light energy is a black surface. For example, the light energy absorbed by black asphalt is converted to heat energy and as a result the asphalt will become warm. Whereas, a white surface will reflect a great amount of light energy and absorb little light. For example, white snow will remain cool because it reflects a lot of the light energy and absorbs little light. ||
 * Types of Substances**
 * Transparent substances will:**
 * transmit or allow light through easily;
 * allow light through them in straight lines;
 * reflect some light;
 * absorb a small amount of light; and
 * allow objects to be seen clearly through them.
 * transmit some light through them;
 * scatter the light in all directions;
 * vary in the amount of light reflected; and
 * not allow objects to be clearly visible through them.
 * Opaque substances will:**
 * not transmit any light;
 * block the light;
 * reflect and absorb light; and
 * not allow any visible object to be seen through them.
 * **Characteristics of Light**

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > Answer > > b. How does this affect the object? > Answer > > > Answer >
 * 1) Light can be reflected, ________(a)________, or ______(b)_______ when it strikes an object.
 * 1) a. How does the amount of light absorbed and reflected vary with light coloured objects compared to dark coloured objects?
 * 1) State whether the following substances are transparent, translucent, or opaque:
 * 2) wax paper
 * 3) a table
 * 4) ice
 * 5) tap water
 * 6) fog

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/external_links.gif caption="Resources Icon"]] Resources
Next
 * 1) How Stuff Works – Types of Materials

Substances that can reflect light to produce an image are called mirrors. The typical mirror is a piece of glass with a thin coating of silver on the on the back. Three types of reflecting surfaces are plane mirrors, convex mirrors , and concave mirrors. ||~ Rear view mirrors in vehicles are an example of a plane mirror. ||
 * **Reflecting Surfaces**

Did you know?
There are several terms used to describe the way light reflects off of shiny surfaces. [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image7.jpeg caption="Image shows the incident ray hitting a plane mirror and the reflecting ray bouncing off the mirror. "]] The angle of incidence equals the angle of reflection for all types of mirrors. The **First Law of Reflection** states: The **Second Law of Reflection** states: Images formed in a mirror have four main characteristics. These characteristics are:
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/did_you_know.gif caption="Did you know icon"]] || Did you know that plane glass mirrors reflect approximately 85% to 90% of the light striking them? The remainder of the light striking a glass mirror is absorbed and converted into heat energy. ||
 * Terms used in the Reflection of Light**
 * 1) The incident ray
 * 2) The reflected ray
 * 3) A normal (N)
 * 4) The angle of incidence
 * 5) The angle of reflection
 * 6) The point of incidence
 * **the angle of incidence = the angle of reflection**
 * **the incident ray, the reflected ray, and the normal all lie on the same plane**
 * **Characteristics of an Image**
 * **Size**: may be smaller than the object viewed, larger than the object viewed, or the same size as the object viewed.
 * **Orientation**: upright (right-side up) or inverted (upside down).
 * **Location** : possible choices are behind the mirror, closer to the mirror, etc.
 * **Type** : a real image or virtual image . ||~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image8.jpeg caption="Image shows a brown vase sitting on the ground in front of a plane mirror. The image of the vase appears to be behind the mirror. "]] The image of the vase is the same size as the vase, upright, behind the mirror, and virtual. ||

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > The Second Law of Reflection states that the ______(c)______ ray, ______(d)______ ray, and the ______(e)______ all lie in the same plane. > Answer > > > Answer >
 * 1) The First Law of Reflection states that the angle of ______(a)______ equals the angle of ______(b)______.
 * 1) State the word that relates to each statement:
 * 2) Refers to whether the image is upright or inverted. _______________
 * 3) The line drawn at right angles to the reflecting surface of the mirror. _________________
 * 4) The angle between the reflected ray and the normal. ________________
 * 5) Type of image formed when the light rays are extended behind the mirror. _________________
 * 6) The ray from the source of light to the point of incidence. _______________

Back | Next A ray diagram can be drawn to show how the image is formed in a mirror. The object viewed in a plane mirror appears to be behind the mirror, which is an optical illusion. The image formed in the mirror has the same characteristics as the object. A ray diagram to locate the image in a plane mirror can be drawn using the following instructions.
 * How Light Reflects from Different Mirrors**
 * A. Plane Mirrors**
 * 1) Draw a line to represent a mirror and shade in one side of the line to represent the reflective coating of the mirror.
 * 2) Draw the object in front of the mirror.
 * 3) Draw in normals from the mirror surface to the ends, middle, or other significant parts of the object.
 * 4) Measure the length of each normal and then draw normals of equal length behind the mirror. The image can be drawn by connecting the ends of the normals on the backside of the mirror.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/example.gif caption="Example Icon"]] Example
[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image9.png caption="Image shows an object which is an arrow and the image on the other side of the mirror. "]] Locating an image in a plane mirror. Normals are drawn from the bottom and the top of the arrow to the mirror in this example. || The images produced in a plane mirror are upright, the same size as the object, flipped sideways (laterally inverted), and the same distance behind the mirror as the object. The image cannot be projected onto a piece of paper therefore, it is considered virtual. These characteristics of plane mirrors make them useful for such things as decorative mirrors in homes, rear view mirrors in vehicles, and mirrors to assist dentists.
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image10.jpeg caption="Image of a child with her mouth open while a dental professional uses a mirror to view her teeth."]] Professionals in the dental field use plane mirrors. ||

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > Answer > > a. > Draw a ray diagram to find the image of the arrow b. >  Draw a ray diagram to find the image of the triangle  Answer >
 * 1) Some of the characteristics of an image in a plane mirror include an image that is upright, the same _______(a)______ as the object, flipped ______(b)_______, and the same _____(c)_______ behind the mirror as the object. The type of image seen in a plane mirror is _____(d)_______.
 * 1) Copy the diagrams in your notebook and, by drawing normals, indicate the location of the image for each of the objects. (Hint: you will need to measure the distance from points on the diagram to the mirror)

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/external_links.gif caption="Resources Icon"]] Resources

 * 1) How Stuff Works – Types of Mirrors

There are some other terms used to study the reflection of light from curved mirrors. These terms are used for convex and concave mirrors. Terminology for curved mirrors || **Characteristics of Convex Mirrors** Objects form an image that is always:
 * B. Curved Mirrors**
 * 1) Centre of curvature (C)
 * 2) Radius of curvature
 * 3) Vertex (V)
 * 4) Principal axis (P.A.)
 * 5) Principal focus (F)
 * 6) Focal length (f)
 * 7) Virtual principal focus (F')


 * smaller
 * upright
 * behind the mirror
 * virtual

The reflecting light rays diverge in front of the mirror so the rays need to be extended behind the mirror to form an image. Convex mirrors have a wide field of view. These mirrors can also make things appear further away than they actually are.
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image14.jpeg caption="Image of a convex mirror with an object in front of it and the image produced behind the mirror."]] Image formed from a convex mirror. ||
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image15.jpeg caption="Image of a convex mirror that bulges outward producing a wider viewing area."]] This convex mirror gives a wide field of view in a parking garage. || The wide field of view present in convex mirrors makes them useful surveillance mirrors. Various uses of convex mirrors include some rear view mirrors in vehicles and security mirrors in department stores, grocery stores, and gasoline stations. ||

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > > Answer > Back | Next
 * 1) State the term that matches with each of the definitions below:
 * 2) the centre of the mirror_____________
 * 3) the distance from the centre of curvature of the mirror surface ____________
 * 4) the distance from the principal focus to the vertex _____________
 * 5) the centre of the sphere that determines the shape of the mirror ____________
 * 6) a point behind a convex mirror _____________

Concave mirrors have a wider range of images compared to convex and plane mirrors. For example objects at a distance from the mirror (beyond the centre of curvature) have an image that is: In this example the light rays converge in front of the mirror to form a real image. ||~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image16.jpeg caption="Image of an object past the centre of curvature with an image produced that is inverted, smaller, and real. "]] Ray diagram for an object placed beyond the centre of curvature. ||
 * **Characteristics of Concave Mirrors**
 * smaller
 * inverted
 * real

The type of image formed will depend on the location of the object in front of the mirror. In this example, the light rays diverge in front of the mirror to form a virtual image behind the mirror. ||~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image17.jpeg caption="Image shows the image of the object as larger, upright, and virtual. "]] Ray diagram for an object placed between the focal point (focus) and the concave mirror. ||
 * Objects that are very close to the mirror (between the principal focus and the mirror) have an image that is:
 * larger
 * upright
 * virtual

"]] Concave mirrors are used in this solar furnace in France. The furnace can reach temperatures up to 3000° C. || Concave mirrors that are pointed towards the Sun will reflect all of the light energy towards one place, the principal focus. This light energy can cause things to heat up and ignite. Some uses of concave mirrors include solar cookers for food, heating water, heating homes, generating electricity, and forming images in telescopes. ||
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/image18.jpeg caption="Image of a solar furnace with many concave mirrors used to produce heat.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the question into your notebook and then check your answer when you are finished your work. > What type of image is formed? Answer >
 * 1) Describe the image formed from the concave mirror below.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229690000/SNC2PPU04A03/images/external_links.gif caption="Resources Icon"]] Resources
Concave Mirrors

=Unit 4: Physics – Light and Applications of Optics=

Activity 4: Refraction of Light
[|Overview] | [|Expectations] | **Content** | [|Assignment]

Content
Refraction is a process that bends light when it travels from one medium into another medium. The light changing speeds as it moves through materials that have different densities causes this bending. The object will appear to be in a different position due to the bending of the light. For example sticks that are partially submerged in water will appear bent because of the refraction of light as it travels from the air to the water. The Law of Refraction states that when light travels from one medium with lower density to another medium with a higher density, the light will bend toward the normal. When light travels from a medium with a higher density to a medium with less density, the light will bend away from the normal. The angle of refraction shows how much the light ray shifted when it enters the new medium. ||~ The straw appears to bend in the blue liquid because of the refraction of light as it moves from the air to the blue liquid. || [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229700000/SNC2PPU04A04/images/image3.jpeg caption="Image shows a light ray moving towards the normal as it moves from air to water. "]] Refraction of light from air to water. The refracted ray moves towards the normal because water is more dense than air. ====Did you know?====
 * **Refraction**
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229700000/SNC2PPU04A04/images/did_you_know.gif caption="Did you know icon"]] || Did you know that the refraction of light through air can form a mirage? Light bends when it travels through air that is different temperatures because warm air is less dense than cold air. ||

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229700000/SNC2PPU04A04/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > Answer > > Answer >
 * 1) _________________ is the bending of light as it travels from one medium to another medium.
 * 1) As you are walking through some lake water you see a large rock in the water a number of steps away. As you step onto the rock it is much deeper than you anticipated. Explain why.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229700000/SNC2PPU04A04/images/external_links.gif caption="Resources Icon"]] Resources

 * 1) How Stuff Works Video – Refracted Light

=Unit 4: Physics – Light and Applications of Optics=

Activity 4: Refraction of Light
[|Overview] | [|Expectations] | [|Content] | **Assignment**

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229700000/SNC2PPU04A04/images/assignment.gif caption="Assignment Icon"]] Assignment
**Complete the following assignment and submit your work to your teacher.** Ensure your name appears on the top of the page.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229700000/SNC2PPU04A04/images/lab.gif width="42" height="42" caption="Lab Icon"]] Laboratory: The Refraction of Light
Before you begin the lab activity, please be sure to download the worksheet to record your answers. ||
 * Purpose:** to investigate the refraction of light as it passes through a variety of media.
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229700000/SNC2PPU04A04/images/stop.gif caption="Stop Icon"]] || ==== ====

> > > > ==== Checklist==== > Your lab report should include the following:
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229700000/SNC2PPU04A04/images/multimedia.gif caption="multimedia icon"]] || Open the Refraction of Light interactive investigation. Follow the instructions on the worksheet and fill in the worksheet as you complete the investigation. ||
 * Discussion:** Answer the following questions in complete sentences and in your own words.
 * 1) ## In scenario 1, does the refracted ray bend away or towards the normal?
 * 2) How did the angle of incidence compare to the angle of refraction in scenario 1?
 * 3) What does this indicate about the type of media in this scenario?
 * 1) ## Compare the angle of refraction in scenario 1 to scenario 2.
 * 2) What does this indicate about the type of media for each scenario?
 * 1) ## What happens to the angle of refraction in scenario 3? Explain.
 * Completed worksheet.
 * Completed discussion questions.

=Unit 4: Physics – Light and Applications of Optics=

Activity 5: Characteristics of Images
[|Overview] | [|Expectations] | **Content** | [|Assignment]

Content
Lenses are curved pieces of glass or other transparent materials that are able to refract light to form images. When light rays pass through a lens, the light is refracted or bent. Two types of lenses are convex and concave lenses. || A concave lens ||  A convex lens ||
 * **Types of Lenses**


 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/image4.jpeg caption="Image shows a convex lens with rays of light directed through the lens."]] Light going through a convex lens bends and converges on the other side of the lens. || A double convex lens is thicker in the centre than at the edges. This type of lens causes light to bend towards the centre of the lens. The light rays will converge at the principal focus (F) and then continue beyond it. The more curved a convex lens is, the greater the refraction of the light. ||

Extending the light rays back until the rays meet forms a virtual image. This can be shown on a ray diagram. ||~ The ray diagram shows when an object is placed closer to the convex lens than the principal focus, a virtual image is produced. The image formed is larger, upright, and virtual. || [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/image6.png caption="Image shows light rays travelling from an object into a convex lens. The light rays bend as they go through the lens and converge on the other side of the lens to form a real image. "]] The ray diagram shows when an object is placed farther from the convex lens than the principal focus, a real image is produced.The image seen in the diagram is smaller, inverted, and real. The images formed by concave (diverging) lenses are only virtual images. A double concave lens is thinner in the centre than at the edges. This type of lens causes light rays to diverge.
 * The image formed by a convex lens can be a real image or a virtual image depending on where the object is placed relative to the principal focus. When an object is placed closer to the convex lens than the principal focus, a virtual image is formed because the light rays do not meet. When an object is placed farther from the convex lens than the principal focus, a real image is formed because the light rays will meet.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > Answer > > b. What type(s) of images are produced by concave lenses? Answer > > Answer > > Answer >
 * 1) The _____(a)______ lens causes the light rays to converge and the _____(b)______ lens causes the light rays to diverge.
 * 1) a. What type(s) of images are produced by convex lenses?
 * 1) Describe the image formed from a convex lens when an object is placed farther than the principal focus.
 * 1) Draw a ray diagram to show the image formed by a convex lens when the object is placed farther out from the principal focus. Label the object and the real image.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/external_links.gif caption="Resources Icon"]] Resources
Next Lenses are useful in optical devices such as cameras, telescopes, binoculars, and microscopes. The eye has its own lens to aid in vision. The clear, flexible, double convex lens in humans is just behind the cornea, aqueous humour, and pupil. The lens is attached to tiny ciliary muscles that help to change the shape of the lens so that an image can be focussed at the back of the eye. ||
 * 1) Refraction by Lenses
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/image7.png caption="Image shows the lens close to the front of the eye which aids in vision."]] The parts of the human eye || **Practical Uses of Lenses**

Did you know?

 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/did_you_know.gif caption="Did you know icon"]] || Did you know that insects have compound eyes that are excellent at detecting motion? The compound eye of insects is made up of many repeating units called ommatidia. Each of these repeating units has its own lens and the brain is able to integrate all of the views into one image. ||

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the question into your notebook and then check your answer when you are finished your work. > Answer >
 * 1) List three uses of lenses.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/external_links.gif caption="Resources Icon"]] Resources
=Unit 4: Physics – Light and Applications of Optics=
 * 1) How Stuff Works - Lenses

Activity 5: Characteristics of Images
[|Overview] | [|Expectations] | [|Content] | **Assignment**

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/assignment.gif caption="Assignment Icon"]] Assignment
**Complete the following assignment and submit your work to your teacher.** Ensure your name appears on the top of the page.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/lab.gif width="42" height="42" caption="Lab Icon"]] Laboratory: Image Formation in Lenses
Before you begin the lab activity, please be sure to download the worksheet to record your answers. ||
 * Purpose:** to investigate the qualitative characteristics of images formed by concave (converging) lenses.
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/stop.gif caption="Stop Icon"]] || ==== ====

> > A number of options are available for submitting your file. Ask your teacher if s/he can read the file format you want to use to create the file. If you do not have software for creating the ray diagram, you may hand draw it. You will submit a photograph or a scan of your ray diagram. > >
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/multimedia.gif caption="multimedia icon"]] || Open the Image Formation in Lenses interactive investigation. Follow the instructions on the worksheet and fill in the worksheet as you complete the investigation. ||
 * Discussion:** Answer the following questions in complete sentences and in your own words.
 * 1) Describe the image as the object is moved
 * 2) close to the convex lens?
 * 3) farther from the principal focus?
 * 4) to the principal focus?
 * 1) Explain your answer in 1 (c).
 * 2) What happens to the light rays during the formation of a real and a virtual image?
 * 3) Draw a ray diagram when the object is placed close to the convex lens. Include labels in your diagram. You may create your ray diagram within your word processor or other software.
 * 1) ## Name the type of lens in the human eye?
 * 2) Where is the image formed in the human eye?
 * 1) How might the lenses in different pairs of eyeglasses vary from each other?

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/checkmark_lg.gif caption="Checkmark Icon"]] Checklist
Your lab report should include the following:
 * Complete worksheet.
 * Complete discussion questions.

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229710000/SNC2PPU04A05/images/external_links.gif caption="Resources Icon"]] Resources
The following resources may be used along with other reputable websites to complete the assignment.
 * 1) Converging Lenses – Ray Diagrams
 * 2) Kids Health – Your Eyes
 * 3) How Stuff Works – Corrective Lenses

=Unit 4: Physics – Light and Applications of Optics=

Activity 6: Additive and Subtractive Colour Theory
[|Overview] | [|Expectations] | **Content** | [|Assignment]

Content
Many colours surround you each day of your life. Colour can be detected by light sensitive nerve cells in the retina of your eyes. Colour can influence the way you dress, the way you feel, and the way you respond to things. For example, traffic lights are specific colours with an important meaning for people. White light can be separated into a band of colours called the visible spectrum using a triangular prism. A rainbow is produced when water droplets in the air act like tiny prisms to separate the white light. ||~ The colours of the rainbow are always in the same order ||
 * Colour**
 * Sir Isaac Newton was the first person to suggest that white light from the Sun was made up of a combination of colours of the rainbow. The main colours of the rainbow are red, orange, yellow, green, blue, and violet.

Did you know?

 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229720000/SNC2PPU04A06/images/did_you_know.gif caption="Did you know icon"]] || Did you know that colours with a shorter wavelength bend more as they move through a prism than colours with a longer wavelength? The colour blue, which has a shorter wavelength, bends more than a colour with a longer wavelength such as red. ||

The Additive Colour Theory is a theory developed by scientists to explain what happens when different colours of light are added together. White light is produced when the six colours of the spectrum are added together. The three additive primary colours can mix together to produce white light. Scientists are not sure why these three colours can produce white light. In addition, the additive primary colours can be combined together in pairs to obtain a new colour. Red and green lights add together to produce yellow light; blue and green lights add together to produce cyan light; and red and blue lights add together to produce magenta light. The colours magenta and cyan are both not part of the visible spectrum of white light. Each of these new colours is called an additive secondary colour. ||~ The three additive primary colours; red, green, and blue. The secondary colours are shown where two colours overlap and the white overlapping section is where all three primary colours overlap. || As well, combining certain secondary and primary colours of equal intensity together can produce white light. For example, when blue (primary colour) is combined with yellow (secondary colour), white light is produced. This happens because yellow light is made up of the colours red and green. As a result, all three primary colours are actually being combined in this case. Two colours added together to produce white light are called complementary colours. (blue + green) || white light || (red + blue) || white light || (red + green) || white light ||
 * **Additive Colour Theory**
 * Complementary Colours**
 * ~ Additive Primary Colour ||~ + Complementary Colour ||~ = Light Transmitted ||
 * red light || cyan light
 * green light || magenta light
 * blue light || yellow light

Access the long description of the table

Did you know?

 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229720000/SNC2PPU04A06/images/did_you_know.gif caption="Did you know icon"]] || Did you know that red-green colour blindness is the most common type of colour blindness? Individuals with this type of colour vision defect will have difficulty distinguishing between red and green colours of a similar tone. Red-green colour blindness is a genetically inherited defect and it affects more males than females. ||

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229720000/SNC2PPU04A06/images/question.gif width="42" height="42" caption="Questions Icon"]] Check Your Understanding
Write the questions into your notebook and then check your answers when you are finished your work. > Answer > > The additive colour theory states that when different colours of light are added together, ______________________________________. > Answer > > > Answer > > > Answer >
 * 1) The three additive primary colours are ______(a)_______, ______(b)________, and _______(c)________.
 * 1) Complete the statement:
 * 1) State the additive primary colours that are added together to produce the following additive secondary colours:
 * 2) yellow = _______________ + _______________
 * 3) magenta = _______________ + _______________
 * 4) cyan = _______________ + _______________
 * 1) ## What is the complementary colour for magenta light?
 * 2) What type of light is produced when two complementary colours are combined?

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229720000/SNC2PPU04A06/images/external_links.gif caption="Resources Icon"]] Resources
Next The Subtractive Colour Theory is a theory that explains what happens when coloured filters are placed over white light. A coloured filter is a transparent object that only allows one colour to pass through. When white light strikes a coloured filter, some of the colours in the visible spectrum are transmitted while others are absorbed and reflected. For example when white light hits a red filter, only the red light in the visible spectrum is transmitted through it and the other colours are absorbed. Therefore we see the colour red. Colours that are absorbed are described as subtracted from the white light. [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229720000/SNC2PPU04A06/images/image4.png caption="Image shows that red light is transmitted and all the other visible colours are absorbed by the red filter. "]] The effect of a red filter on white light When a blue filter and then a red filter are placed in front of white light, there is no light transmitted through the second filter and the red filter appears black. This occurs because the blue filter will allow blue light to pass through, but when the blue light strikes the red filter, the blue light is subtracted or absorbed by the red filter. As a result all of the incident white light has been subtracted. [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229720000/SNC2PPU04A06/images/image5.png caption="Image of white light approaching a blue filter and blue light is transmitted. Then the blue light is absorbed by the red filter. "]] There is no light transmitted when a blue and red filter are placed in front of white light. ====Did you know?==== A combination of filters produces black when all the light striking the filters has been absorbed and there is no light transmitted. ||
 * 1) Colour and Vision
 * 2) Colour blindness
 * The Subtractive Colour Theory**
 * ~ [[image:http://download.elearningontario.oise.utoronto.ca/repository/1229720000/SNC2PPU04A06/images/did_you_know.gif caption="Did you know icon"]] || Did you know that black is not a colour, but instead it is the absence of colour?


 * The subtractive primary colours absorb or subtract one of the additive primary colours as light passes through them.

A magenta filter transmits red and blue light, and subtracts green light. A yellow filter transmits red and green light, and subtracts blue light. A cyan filter transmits green and blue light, and subtracts red light. When the three subtractive primary colour filters combine, black is produced because all of the light is absorbed. Different combinations of yellow, magenta, and cyan colours are able to produce many transmitted colours. ||~ The primary subtractive colours are yellow, magenta and cyan || Certain subtractive secondary colour filters can be combined with subtractive primary colours to produce no light and the area will appear black. For example, when a yellow filter is combined with a blue filter there will be no light transmitted and the area will appear black. Other combinations that produce no light are: magenta filter + green filter cyan filter + red filter A yellow filter subtracts blue light and transmits red and green light. A magenta filter subtracts green light and transmits red and blue light. A cyan filter subtracts red light and transmits green and red light. ==== Check Your Understanding==== Write the questions into your notebook and then check your answers when you are finished your work. > The subtractive primary colours are ______(b)_______, ______(c)________, and _____(d)________. > The subtractive secondary colours are ______(e)______, ______(f)_______, and _______(g)______. > Answer > > > Answer > > Answer > > > Answer >
 * 1) The Subtractive Colour Theory states that the object absorbs or _____(a)_______ one or more components of the incident light.
 * 1) ## What colour(s) would be seen when white light goes through a blue filter?
 * 2) What colour(s) in the white light are absorbed by a blue filter?
 * 3) What colour(s) in the white light are transmitted by a blue filter?
 * 1) Describe what happens when white light goes through a red filter followed by a yellow filter.
 * 1) State the colour transmitted in the following cases:
 * 2) magenta, cyan, and yellow light are combined
 * 3) red, green, blue light are combined
 * 4) red, green, and blue light strike a cyan filter
 * 5) red, green, and blue light strike a magenta filter

[[image:http://download.elearningontario.oise.utoronto.ca/repository/1229720000/SNC2PPU04A06/images/external_links.gif caption="Resources Icon"]] Resources

 * 1) Colour Subtraction