chapter 13 - electromagnetic waves

Question 1

explain why EM waves are not mechanical waves?

Answer 1

they can travel through a vacuum (dont need a substance to travel through)

Question 2

different types of waves in the EM spectrum in order of decreasing wavelength (increasing frequency)?

Answer 2

order of longest - shortest:

• radio
• microwave
• infrared
• visible
• ultraviolet
• x-rays
• gamma

Question 3

how are gamma rays produced?

Answer 3

changes in the nucleus of an atom (during radioactive decay)

Question 4

how can radio waves be produced?

Answer 4

oscillations in an electrical circuit

Question 5

how do you detect radio waves?

Answer 5

waves are absorbed and create an alternating current with the same frequency as the radio wave

Question 6

what are radio waves used for?

Answer 6

• transmitting television
• mobile phone
• bluetooth signals

Question 7

what are microwaves used for?

Answer 7

• satellite communications

- cooking food

Question 8

what is infrared radiation used for?

Answer 8

• heating
• remote controls
• infrared cameras
• cooking food

Question 9

what types of EM waves are harmful to the human body?

Answer 9

• ultraviolet
• x-rays
• gamma rays

Question 10

what are the hazards of being exposed to ultraviolet radiation?

Answer 10

• damage to skin cells
• sunburn
• increased risk of skin cancer
• skin aging prematurely
• blindness

Question 11

why are x-rays used for medical imaging?

Answer 11

they pass through flesh but not bone

Question 12

why are gamma rays used for treating cancer and sterilising medical equipment?

Answer 12

high doses kill cells and bacteria

Question 13

characteristics on gamma rays?

Answer 13

• very short wavelengths
• high frequency
• most energetic
• used for:
• • radiotherapy
• • medical tracers
• • sterilising equipment
• hazards:
• • can ionise atoms in DNA, which can lead to mutations

Question 14

characteristics on x-rays?

Answer 14

• used for:
• • looking at bones
• hazards:
• • can ionise atoms in DNA, which can lead to mutations

Question 15

characteristics on unltraviolet?

Answer 15

• used for:
• • tanning beds
• • curing gel polish
• • anti-counterfeiting
• hazards:
• • can ionise atoms in DNA, which can lead to mutations

Question 16

characteristics on visible light?

Answer 16

• used for:
• • seeing
• • photography
• hazards:
• • too much can damage the retina

Question 17

characteristics on infrared?

Answer 17

• used for:
• • thermal imaging
• • heating
• • remote controls
• hazards:
• • can lead to hyperthermia (too hot)

Question 18

characteristics on microwaves?

Answer 18

• used for:
• • heating food
• • communications
• • satellite communication
• hazards:
• • low hazard

Question 19

characteristics on radio waves?

Answer 19

• very long wavelength
• low frequency
• least energetic
• used for:
• • bluetooth
• • radio
• • long distance communications
• hazards:
• • low hazard

Question 20

leslie cube - most to least infrared emmision?

Answer 20

most
- matte black
- shiny black
- white
- shiny metallic
least