Optics Review (Chapters 11, 12, 13)

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1 Optics Review (Chapters 11, 12, 13) Complete the following questions in preparation for your test on FRIDAY. The notes that you need are in italics. Try to answer it on your own first, then check with your notes. Answers will be posted on the website by Thursday afternoon. Note: 11.1 Light and the Electromagnetic Spectrum a) Define the electromagnetic spectrum. b) Name the 7 types of radiation. c) How does the wavelength and frequency change as you go from radio waves to gamma waves? d) Which type of rays are more hazardous to our health: UV rays or gamma rays? Why? Note: 11.2 Producing Visible Light a) Give an example of natural light. b) Give an example of artificial light. c) List the 6 types of light we discussed. d) Determine what type of light is illustrated by each of the following examples. Then explain how you know. lightning Example Type of Light Explanation lightbulb in the lights on the ceiling of this classroom black light glow stick glow-in-the-dark plastic star shapes the first lightbulb ever invented a glow worm e) How are chemiluminescence and bioluminescence related? f) Why would chemiluminescence sometimes be referred to as cool light? Note: 11.4, 11.5 Additive and Subtractive Colour Theory a) Violet coloured light differs from red light because it has a higher but a smaller. b) White light is composed of the following primary colours of light:,,. c) If you mix two primary colours, you get a colour. d) Magenta light = light + light.

2 e) Magenta + cyan light = light. f) When you mix two colours together and you get white light, this means they are colours. g) Fill in the following table: transparent Term Definition Example some of the light passes through the object A piece of construction paper. h) The subtractive theory of light applies to and whether they absorb or reflect certain colours of light. i) Draw diagrams showing what happens when: i. white light hits a green object ii. red light hits a blue object iii. cyan light hits a yellow object iv. blue light hits a yellow object Note: Human Vision a) What are the differences between rods and cones? b) If cones only sense the primary colours, how are you able to see all of the colours in between? c) How is the light information detected by photoreceptors sent to the brain for processing? Note: 12.1 Light Rays and Reflection a) Draw a ray diagram to illustrate the Law of Reflection. Be sure to label: the incident ray, the reflected ray, the angle of incidence, the angle of reflection, and the normal. b) What is the difference between regular reflection and diffuse reflection? Note: 12.5 Curved Mirrors a) Draw a ray diagram for a concave mirror where the object is just past the focal point. Label the focal point (F), the vertex, the principal axis, the object, and the image. Determine the location, orientation, size and type of image that is produced. b) Draw a ray diagram for a concave mirror where the object is between the focal point and the mirror. Label the focal point (F), the vertex, the principal axis, the object, and the image. Determine the location, orientation, size and type of image that is produced. c) Draw a ray diagram for a convex mirror. Label the focal point (F), the vertex, the principal axis, the object, and the image. Determine the location, orientation, size and type of image that is produced. d) Give 3 examples of where curved mirrors are used in real life. Note: 13.1 Refraction a) Define refraction. Be sure to include why it happens in your definition. b) Define index of refraction. c) As a medium gets denser, what happens to its index of refraction? d) What are all other mediums compared to when determining their indices of refraction?

3 e) When light passes from a medium of high density (or with a high index of refraction), to low density, light bends from the normal. f) Draw a diagram of the situation from e). Label, the normal, the angle of incidence and the angle of refraction. g) When light passes from a medium of low density (or with a low index of refraction) to a high density, light bends from the normal. h) Draw a diagram of the situation from g). Label, the normal, the angle of incidence and the angle of refraction. i) Define total internal reflection. j) What does the critical angle have to do with total internal reflection? Worksheet: 13.3 Converging and Diverging Lenses a) What is a lens? b) What is the difference between a converging and diverging lens in terms of: i. shape ii. how they refract light Worksheet: 13.5 Ray Diagrams with Lenses a) Draw a diagram showing the image that is produced when an object is just past F using a converging lens. Determine the location, orientation, size and type of image that is produced. b) Draw a diagram showing the image that is produced when an object is between F and a converging lens. Determine the location, orientation, size and type of image that is produced. c) Draw a diagram showing the image that is produced when an object is just past F using a diverging lens. Determine the location, orientation, size and type of image that is produced. Note: 13.6 Optical Devices a) How do magnifying lenses work? b) How are cameras similar to magnifying glasses? c) How are cameras different from magnifying glasses? d) How do refracting telescopes work? e) How is your eye like a camera? f) What is the role of: cornea pupil iris retina lens g) If you are far-sighted, you can see, but objects that are. You need lenses. h) If you are near-sighted, you can see, but objects that are. You need lenses.

4 Optics Review (Chapters 11, 12, 13) Complete the following questions in preparation for your test on FRIDAY. The notes that you need are in italics. Try to answer it on your own first, then check with your notes. Answers will be posted on the website by Thursday afternoon. Note: 11.1 Light and the Electromagnetic Spectrum a) Define the electromagnetic spectrum. The range of light-like waves. b) Name the 7 types of radiation. Radio waves, microwaves, visible light, infrared, UV rays, X rays, gamma rays c) How does the wavelength and frequency change as you go from radio waves to gamma waves? The wavelength gets smaller and the frequency increases. d) Which type of rays are more hazardous to our health: UV rays or gamma rays? Why? Gamma rays because they have a high frequency - that means more energy and more damage to cells. Note: 11.2 Producing Visible Light a) Give an example of natural light. The sun, bioluminescence b) Give an example of artificial light. lightbulbs (incandescence) c) List the 6 types of light we discussed. bioluminescence, incandescence, fluorescence, phosphorescence, chemiluminescence, electroluminescence d) Determine what type of light is illustrated by each of the following examples. Then explain how you know. Example Type of Light Explanation lightning IGNORE lightbulb in the lights on the ceiling of this classroom fluorescence Those lightbulbs use UV radiation to make light. black light fluroescence Black lights use UV light bulbs glow stick chemiluminescence When the glow stick is cracked, the chemicals mix and glow. glow-in-the-dark plastic star shapes phosphorescence Things that glow on their own are phosphorescent. the first lightbulb ever invented incandescence Old lightbulbs use filaments that heat up and glow when heat is passed through them. a glow worm bioluminescence Glow worms are animals that create their own light. e) How are chemiluminescence and bioluminescence related? Animals use chemicals are create light. f) Why would chemiluminescence sometimes be referred to as cool light? It doesn t create any heat.

5 Note: 11.4, 11.5 Additive and Subtractive Colour Theory a) Violet coloured light differs from red light because it has a higher frequency but a smaller wavelength. b) White light is composed of the following primary colours of light: red, green, blue. c) If you mix two primary colours, you get a secondary colour. d) Magenta light = red light + blue light. e) Magenta + cyan light = white light. f) When you mix two colours together and you get white light, this means they are complementary colours. g) Fill in the following table: Term Definition Example transparent all rays pass through glass transluscent some of the light passes through the object frosted glass opaque no rays pass through A piece of construction paper. h) The subtractive theory of light applies to pigments and whether they absorb or reflect certain colours of light. i) Draw diagrams showing what happens when: i. white light hits a green object green reflected ii. red light hits a blue object object is black, nothing reflected iii. cyan light hits a yellow object green reflected iv. blue light hits a yellow object object is black, nothing reflected Note: Human Vision a) What are the differences between rods and cones? Rods detect movements, low light conditions; cones detect light. b) If cones only sense the primary colours, how are you able to see all of the colours in between? You have three types of cones; if more than one is activated, your brain mixes the colours. c) How is the light information detected by photoreceptors sent to the brain for processing? Sent to the brain via the optic nerve. Note: 12.1 Light Rays and Reflection a) Draw a ray diagram to illustrate the Law of Reflection. Be sure to label: the incident ray, the reflected ray, the angle of incidence, the angle of reflection, and the normal.

6 b) What is the difference between regular reflection and diffuse reflection? In regular, all rays of light are reflected in the same direction but not in diffuse because the surface is bumpy. Note: 12.5 Curved Mirrors a) Draw a ray diagram for a concave mirror where the object is just past the focal point. Label the focal point (F), the vertex, the principal axis, the object, and the image. Determine the location, orientation, size and type of image that is produced.

7 b) Draw a ray diagram for a concave mirror where the object is between the focal point and the mirror. Label the focal point (F), the vertex, the principal axis, the object, and the image. Determine the location, orientation, size and type of image that is produced. c) Draw a ray diagram for a convex mirror. Label the focal point (F), the vertex, the principal axis, the object, and the image. Determine the location, orientation, size and type of image that is produced.

8 d) Give 3 examples of where curved mirrors are used in real life. Security mirrors, solar cookers, rearview mirrors... Note: 13.1 Refraction a) Define refraction. Be sure to include why it happens in your definition. When light changes its path when it goes from one medium to another. b) Define index of refraction. The number given to a medium to show how much light changes speed through it. c) As a medium gets denser, what happens to its index of refraction? The higher the number the more dense it is and the slower light will travel. d) What are all other mediums compared to when determining their indices of refraction? Air/vacuum e) When light passes from a medium of high density (or with a high index of refraction), to low density, light bends away from the normal. f) Draw a diagram of the situation from e). Label, the normal, the angle of incidence and the angle of refraction. g) When light passes from a medium of low density (or with a low index of refraction) to a high density, light bends towards the normal. h) Draw a diagram of the situation from g). Label, the normal, the angle of incidence and the angle of refraction.

9 i) Define total internal reflection. When light reflects completely off the inside of a medium rather than passing through it to the next medium. j) What does the critical angle have to do with total internal reflection? Once the light has reached the critical angle, the light does not pass through the medium and as the angle increases, total internal reflection occurs. Worksheet: 13.3 Converging and Diverging Lenses a) What is a lens? Optical device that refracts light. b) What is the difference between a converging and diverging lens in terms of: i. shape ii. how they refract light See above Worksheet: 13.5 Ray Diagrams with Lenses a) Draw a diagram showing the image that is produced when an object is just past F using a converging lens. Determine the location, orientation, size and type of image that is produced.

10 L: on the other side of the lense O: inverted S: bigger T: real b) Draw a diagram showing the image that is produced when an object is between F and a converging lens. Determine the location, orientation, size and type of image that is produced. L: behind the object O: upright S: bigger T: virtual c) Draw a diagram showing the image that is produced when an object is just past F using a diverging lens. Determine the location, orientation, size and type of image that is produced. L: in front of the object O: upright S: smaller T: virtual Note: 13.6 Optical Devices a) How do magnifying lenses work? Use a converging lens, create a bigger, virtual image b) How are cameras similar to magnifying glasses? They also use a converging lens c) How are cameras different from magnifying glasses? They create a real, smaller image d) How do refracting telescopes work? They use two converging lenses to create two images (you only see one) e) How is your eye like a camera? We also have a lens that focus light on the retina f) What is the role of: cornea pupil Refracts light as it passes through Hole that lets light through

11 iris retina lens Changes the shape of the pupil to let more or less light in Has photoreceptors that detect light Changes shape in order to focus the image g) If you are far-sighted, you can see distant objects, but NOT objects that are close-up. You need convex (converging) lenses. h) If you are near-sighted, you can see close-up, but NOT objects that are distant. You need concave (diverging) lenses.