Grade 8 Light and Optics Unit exam
Unit C - Light and Optics 1. Over the years many scientists have contributed to our understanding of light. All the properties listed below about light are correct except: a. light is a form of heat b. light travels in straight lines c. light can bend on it s own d. light can be reflected 2. All the statements below are true except a. visible light is made up of more than one color b. glass can bend light rays c. light travels in straight parallel lines unless diffuse reflection occurs d. the speed of light is about 1000m/s 3. When looking into a shop window on a bright sunny day you see an image that is a mixture of you image and the items on display in the store. The principles of light involved are a. reflection and absorption b. refraction and absorption c. refraction and transmission d. reflection and transmission 4. Why does your body cast a shadow on a wall? a. light travels in straight lines but your body absorbs and blocks some light b. your body refracts some light so the image appears larger c. light travels in straight lines until it encounters and object then it bends d. your body absorbs some light and magnifies the remainder 5. On a calm morning in Banff, a lake is so smooth it looks like the surface of a mirror in which you can see and image of the mountains on the lake surface. Which of the following statements about the reflection on the lake is correct? a. you are viewing the incident rays coming from the lake surface b. you are viewing the reflected rays coming from the lake surface c. you are viewing the reflected rays directly from the mountains d. you are viewing the incident rays from the mountains 6. What angle does the normal make with a mirror a. 0 b. 45 c. 90 d. 180 2
7. The difference between a convex lens and a concave lens is a.convex lenses are thicker in the middle. b.concave lenses are thicker in the middle c.convex lenses spreads out light rays d.concave lenses concentrate the light 8. Which of the following statements about compound light microscopes is correct? a.lenses bend the light to reduce the image b.lenses bend the light to enlarge the image c.mirrors reflect the light to enlarge the image d.mirrors refract the light to enlarge the image 9. Two characteristics that make telescopes useful for observing the sky are their ability to a.separate and magnify light b.magnify and collect light c.collect and separate light d.magnify and clarify light 10. Binoculars are most similar to a pair of telescopes fixed together. They are constructed so that light will pass through the following structures in this order a. eyepiece, mirror, prism, objective lens b. objective lens, prism, eyepiece c. objective lens, mirror, eyepiece d. objective lens, prism, mirror, eyepiece 11. The structure of the eye and a simple camera are very similar. The following structures are correctly paired except a. retina film b. pupil aperture c. iris diaphragm d. lens shutter 12. The structure controlling the amount of light entering the eye is the a. cornea b. iris c. pupil d. retina 3
13. Which structures in the eye are responsible for color vision and black and white vision in that order? a. retina and optic nerve b. rods and optic nerve c. rods and cones d. cones and rods 14. Insect eyes differ from the eyes of animals such as a cat in that a. insects have simple eyes and cats have compound eyes b. cats have compound eyes and insects have camera eyes c. insects have compound eyes and cats have simple eyes d. cats have camera eyes and insects have compound eyes Use the diagram below to answer the following 3 questions. 15. The diagram above illustrates a. The Law of Refraction b. The Law of Reflection c. The Law of Diffusion d. The Law of Incidence 16. What does the I represent? a. Initial b. Intense c. Incident d. Inverse 17. If θi is increased, what will happen to θr? a. Increases b. Decreases c. Stays the same d. Disappears 4
Use the following diagram to answer the following question. 18. What type of reflection is illustrated above? a. Regular b. Plane c. Smooth d. Diffuse Use the diagram below to answer the following question. 19. The mirror illustrated above is showing the light rays a. Converging b. Diverging c. Submerging d. Refracting 5
Use the diagram below to answer the following 3 questions. Object 20. The type of mirror illustrated in the diagram above is a a. Plane b. Convex c. Concave d. None of the above 21. What does the F in the diagram represent? a. Figure point b. Function point c. Forward point d. Focal point 22. The mirror illustrated above is showing the light rays a. Converging b. Diverging c. Submerging d. Refracting 23. A process that causes a light beam to change direction because its speed has changed is called a. Reflection b. Convergence c. Refraction d. Divergence 24. What happens light as it moves from air into water? a. Bends and lines up with the normal b. Bends towards the normal c. Bends away from the normal d. None of the above 6
25. Concave lenses are a. Thick in the middle and thick at the edges b. Thin in the middle and thin at the edges c. Thin in the middle and thick at the edges d. Thick in the middle and thin at the edges 26. The human eye operates most closely like a a. Telescope b. Microscope c. Camera d. Prism 27. When a person sees something, which of the following carries the message from the eye to the brain? a. Muscles b. Nerves c. Arteries d. Veins 28. An image of a person is visible through the sheer drapes of an office. This is possible because the ceiling light is, the drapes are and the person is. a. luminous, opaque, translucent b. transparent, translucent, opaque c. translucent, transparent, opaque d. luminous, translucent, opaque 29. When drawing diagrams to show how mirrors reflect light, you would label the ray of light coming to the mirror as the a. Reflective ray. b. Diffuse ray c. Transparent ray d. Incident Ray 30. The part of your eye that is photosensitive and converts light energy into nerve impulses is called the a. The cornea b. The retina c. The blind spot d. The lens 7
Use the following information to answer the next 2 questions. Since John started grade 8 he has found it hard to focus on objects that are close. John s mother takes him to the eye doctor and the doctor prescribes a pair of glasses for him to use when he is reading or watching television. The eye doctor recommended laser eye surgery. 31. A reasonable diagnosis of John s vision is: a. Near-sightedness b. Astigmatism c. Far-sightedness d. Blindness 32. The lasers used in eye surgery a. reshape the lens of the eye b. remove the outer layers of the lens c. reshape the cornea of the eye d. remove the inner layer of the cornea 33. The difference between a high resolution digital camera and a low resolution digital camera is that the screens of a. high resolution cameras use the same number of pixels but more colours b. low resolution cameras use fewer pixels but the same number of colours c. high resolution cameras use more colours and fewer pixels d. low resolution cameras use more pixels and fewer colours 34. The part of a digital camera that converts light into digital information is the a. film b. aperture c. video recorder d. charge-coupled device 35. Which lens is used to correct far-sightedness, and how does this lens correct the vision? a. Convex lens, which allows the image to fall on the retina b. Convex lens, which allows the image to fall behind the retina c. Concave lens, which allows the image to fall on the retina d. Concave lens, which allows the image to fall behind the retina 8