Question

1. in terms of heat transfer, how is radiation different from conduction and convection?
2. what two major properties did maxwell predict that electromagnetic waves would possess?
3. what two discoveries confirmed the existence of electromagnetic waves?
4. write these electromagnetic waves in order from lowest energy to highest energy: infrared light, x - rays, red light, gamma rays, and microwaves.
5. sunscreen, if used properly, can protect you from getting a sunburn. from which electromagnetic waves must sunscreen protect the skin?
6. list the seven colours that newton identified in the visible spectrum of white light.
7. why is it useful to examine the universe using parts of the electromagnetic spectrum other than visible light?
8. list some devices that you have used or plan to use today that involve electromagnetic waves.
9. match each electromagnetic wave from column a with the term from column b that is most closely related.

column a
(a) x - rays
(b) ultraviolet light
(c) radio waves
(d) infrared light
(e) microwaves
(f) gamma rays
(g) visible light
column b
vitamin d
telecommunications
cancer treatment
radar
theatre/concert effects
baggage screening
dvd player remote control

Explanation:

1. Radiation transfers heat through electromagnetic waves without a medium. Conduction needs a solid medium and convection a fluid medium.
2. Maxwell predicted electromagnetic waves would travel at the speed of light and be transverse waves.
3. Hertz's experiments generating and detecting radio - waves and the photoelectric effect confirmed electromagnetic waves.
4. Energy of electromagnetic waves is related to frequency. Lower frequency means lower energy. So the order is microwaves, infrared light, red light, X - rays, gamma rays.
5. Sunscreen protects from ultraviolet light which can cause sunburn.
6. Newton identified red, orange, yellow, green, blue, indigo, and violet in the visible spectrum of white light.
7. Different parts of the electromagnetic spectrum can reveal different information about celestial objects not visible in visible light, like radio waves can show cold gas clouds.
8. Devices like mobile phones (radio waves), remote controls (infrared light), microwaves (microwaves) use electromagnetic waves.
9. (a) X - rays - baggage screening; (b) ultraviolet light - vitamin D; (c) radio waves - telecommunications; (d) infrared light - DVD player remote control; (e) microwaves - radar; (f) gamma rays - cancer treatment; (g) visible light - theatre/concert effects.

Answer:

1. Radiation transfers heat through electromagnetic waves without a medium, while conduction needs a solid medium and convection needs a fluid medium.
2. Travel at the speed of light and be transverse waves.
3. Hertz's experiments generating and detecting radio - waves and the photoelectric effect.
4. Microwaves, infrared light, red light, X - rays, gamma rays.
5. Ultraviolet light.
6. Red, orange, yellow, green, blue, indigo, violet.
7. Different parts of the electromagnetic spectrum can reveal different information about celestial objects not visible in visible light.
8. Mobile phones, remote controls, microwaves (answers may vary).
9. (a) - baggage screening; (b) - vitamin D; (c) - telecommunications; (d) - DVD player remote control; (e) - radar; (f) - cancer treatment; (g) - theatre/concert effects.