Chapt. 14 EM Waves

Question 1

What are the 8 properties of an EM wave?

Answer 1

• EM waves are transverse waves.
• EM waves can travel through vacuum.
  (do not require a medium to travel)
• EM waves transfer energy from one place to another.
• EM waves all travel at 3.0x108 m/s in vacuum.
• The equation, v=fλ, is applicable to all EM waves.
• When an EM wave travels from one medium to another, it’s frequency remains constant while it’s speed and wavelength changes.
• EM waves obey the laws of reflection and refraction.
• EM waves don’t carry electric charges.

Question 2

What is the relationship between the frequency of an EM wave and it’s energy?

Answer 2

The higher the frequency of the EM wave, the higher it’s energy.

Question 3

List the types of EM waves from increasing frequency.

Answer 3

Radiowaves
Microwaves
Infrared waves
Visible light
Ultra-violet waves
X-Rays
Gamma rays

Question 4

List the types of EM waves from increasing wavelength.

Answer 4

Gamma rays
X-Rays
Ultra-violet rays
Visible light
Infrared rays
Microwaves
Radiowaves

Question 5

List the EM waves in terms of decreasing wavelength.

Answer 5

Radiowaves
Microwaves
Infrared waves
Visible light
Ultra-violet rays
X-Rays
Gamma rays

Question 6

List the types of EM waves in terms of decreasing frequency.

Answer 6

Gamma rays
X-Rays
Ultra-violet rays
X-Rays
Visible light
Infrared rays
Microwaves
Radiowaves

Question 7

What is the range of wavelengths of visible light, from red to violet?

Answer 7

~700nm-~400nm

Question 8

What are the applications of radiowaves?

Answer 8

Radios
Over-the-air television
Communications

Radiowaves of longer wavelengths can travel around obstructions better than those of shorter wavelengths.

Question 9

What are the applications of microwaves?

Answer 9

Microwave ovens:
They are used in microwave ovens to transfer energy. Microwaves penetrate5the food and cause the water molecules within to vibrate vigorously. These molecular vibrations generate heat that eventually spreads throughout the food.

Satellite television
Microwaves can penetrate the atmosphere.
Global Positioning System (GPS)
Microwaves can carry signals in a mobile phone network.

Question 10

What are the applications of infrared radiation?

Answer 10

Remote controllers
Infrared remote controllers are used to control a variety of electrical devices.

Ear thermometers
Human body gives out IR radiation. Amt of IR emitted from body depends on temp. Ear thermometers measure the amt of IR radiation to determine the body temp.

Intruder alarms
Detect changes in IR radiation in the environment