1. Sources & Properties of Light
Chapter 10 Review
Sources & Properties of Light

2. Give an example of a phosphorescent light source.
Category: Light Energy & Its Sources
Give an example of a phosphorescent light source.
Any objects that glow in the dark
Ex. Dials on watches, stickers, etc.

3. Category: Electromagnetic Spectrum
What happens to the wavelength of electromagnetic radiation as you move from radio waves through to gamma rays?
The wavelength decreases.

4. What are luminous objects?
Category: Light Energy & Its Sources
What are luminous objects?
Objects that give off light energy.

5. Explain how an incandescent light bulb works.
Category: Light Energy & Its Sources
Explain how an incandescent light bulb works.
Electrical energy travels through the tungsten wire, making it so hot that it glows.

6. Which wave has the higher frequency? Which has the longer wavelength?
Category: Properties of Waves
Which wave has the higher frequency? Which has the longer wavelength?
Wave Y has the higher frequency.
Wave X has the longer wavelength.

7. Category: Light Energy & Its Sources
Define light.
A form of energy that can be detected by the human eye.

8. How do we see objects as white? How do we see objects as black?
Category: Visible Spectrum
How do we see objects as white? How do we see objects as black?
Objects appear white when they reflect all parts of the visible spectrum. They appear black when they absorb all (reflect none) of the parts of the visible spectrum.

9. What parts of a wave are label 1 and label 2?
Category: Properties of Waves
What parts of a wave are label 1 and label 2?
1 is the crest and 2 is the trough.

10. Explain how a fluorescent light works.
Category: Light Energy & Its Sources
Explain how a fluorescent light works.
Electricity passes through mercury gas, causing it to release UV light. This light is then absorbed by the phosphor coating on the inside of the tube, causing it to give off visible light.

11. What are the two ways that we can see light?
Category: Light Energy & Its Sources
What are the two ways that we can see light?
Light can either travel directly from the source to our eyes or indirectly, by bouncing off an object first.

12. What is chemiluminescence?
Category: Light Energy & Its Sources
What is chemiluminescence?
The process of emitting light energy when two or more chemicals mix together.

13. Category: Light Energy & Its Sources
What is the big disadvantage with using incandescent light bulbs over, say, fluorescent lights?
They are extremely inefficient since most of the electrical energy becomes thermal energy (heat) rather than light.

14. What is electric discharge?
Category: Light Energy & Its Sources
What is electric discharge?
The process of emitting light because of
electricity passing through a gas.

15. Is the Moon a luminous or nonluminous object? Explain.
Category: Light Energy & Its Sources
Is the Moon a luminous or nonluminous object? Explain.
Nonluminous since it is not the source of light, but rather it reflects light from the Sun.

16. Category: Properties of Waves
The distance from the resting position to a crest or trough is called what? (Label 3).
Amplitude.

17. What is bioluminescence? Give an example.
Category: Light Energy & Its Sources
What is bioluminescence? Give an example.
When chemiluminescence occurs in living things (two chemicals in the creature mix together to produce light). Some fish, squid, bacteria, fungi, fireflies.

18. Give two examples of electric discharge.
Category: Light Energy & Its Sources
Give two examples of electric discharge.
Lightning and neon signs.

19. Explain how a phosphorescent light source works.
Category: Light Energy & Its Sources
Explain how a phosphorescent light source works.
When you shine light on a phosphorescent light source, the phosphors in the object store the energy and release it gradually as light energy.

20. Category: Getting in Light’s Way
What is a shadow?
An area where light has been blocked by a solid object.

21. Category: Light Energy & Its Sources
What is the main difference between a fluorescent and a phosphorescent light source?
A fluorescent source emits light only while it is receiving energy from another source. A phosphorescent source can continue to emit light for some time after the source of energy is removed.

22. Explain why we can’t see an object when it is behind another.
Category: Getting in Light’s Way
Explain why we can’t see an object when it is behind another.
The light rays from the farther object are being blocked from entering our eyes by the closer object. (Light travels in straight lines).

23. In what situation would a shadow have both an umbra and a penumbra?
Category: Getting in Light’s Way
In what situation would a shadow have both an umbra and a penumbra?
When there is more than one light source or if the light source is very large relative to the object.

24. What is the wavelength and amplitude of the wave?
Category: Properties of Waves
What is the wavelength and amplitude of the wave?
The wavelength is 4 metres and the amplitude is 2 metres.

25. Category: Getting in Light’s Way
In a cold climate, state what type of materials would be best for building a house: Dark or light? Shiny or dull? Rough or smooth? Why?
Dark, dull, rough materials would be best because they absorb much of the light energy to become heat energy (helps to heat the house).

26. What is the difference between a transparent and a translucent object?
Category: Getting in Light’s Way
What is the difference between a transparent and a translucent object?
A transparent object will transmit light (allow all of it to pass through) so that a clear image can been seen through it. A translucent object will transmit some but also reflect some of the light so that a fuzzy image is seen through it.

27. Name and briefly explain the two parts of a shadow.
Category: Getting in Light’s Way
Name and briefly explain the two parts of a shadow.
The umbra is the dark part of a shadow. The penumbra is the lighter part of a shadow (not always present).

28. Category: Getting in Light’s Way
Does a transparent object transmit, reflect, or absorb light? (You can pick more than one of these if needed.)
Transmit.

29. What is frequency and what is its unit?
Category: Properties of Waves
What is frequency and what is its unit?
Frequency is the number of occurrences
(ex. waves) in a period of time (cycles per second). Its unit is hertz (Hz).

30. What happens to the light that tries to pass through an opaque object?
Category: Getting in Light’s Way
What happens to the light that tries to pass through an opaque object?
Some is absorbed and some is reflected.

31. In terms of transparency, how would you classify a mirror? Why?
Category: Getting in Light’s Way
In terms of transparency, how would you classify a mirror? Why?
A mirror is an opaque object because light cannot pass through it. Rather, it is reflected.

32. Name, in order, the colours of the visible spectrum.
Category: Visible Spectrum
Name, in order, the colours of the visible spectrum.
Red, orange, yellow, green, blue, indigo, and violet (ROY G BIV).

33. What did Newton discover about light?
Category: Visible Spectrum
What did Newton discover about light?
That white light is made up of the spectral colours (red through violet).

34. Explain how we see an object as green.
Category: Visible Spectrum
Explain how we see an object as green.
The object is reflecting the green part of the visible spectrum (and is absorbing the waves corresponding to the other parts of the spectrum).

35. Category: Electromagnetic Spectrum
What happens to the frequency and energy of electromagnetic radiation as you move from radio waves through to gamma rays?
The frequency and energy of the waves increase.

36. Which colour of light has the shortest wavelength: blue or orange?
Category: Electromagnetic Spectrum
Which colour of light has the shortest wavelength: blue or orange?
Blue (the waves are closer together).

37. Category: Getting in Light’s Way
Does a translucent object transmit, reflect, or absorb light? (You can pick more than one of these if needed)
Transmit and reflect.

38. What is the relationship between wavelength and frequency of a wave?
Category: Properties of Waves
What is the relationship between wavelength and frequency of a wave?
As wavelength increases (as waves get longer), frequency decreases (number of waves in a given amount of time decreases).

39. Category: Light Energy & Its Sources
What kind of light source is a light stick (glow stick)? Explain how a light stick works.
Chemiluminescent source. A thin wall separates two chemicals that, when mixed, react to produce light.

40. Category: Light Energy & Its Sources
What is incandescence?
The process of emitting light because of high temperatures.

41. Category: Electromagnetic Spectrum
Which of the following electromagnetic waves has the highest energy: radio, ultraviolet, or x-rays?
X-rays because they have the highest frequency (and therefore shortest wavelength).