P5.2 - Electromagnetic Fields

Question 1

what angle do electromagnetic fields oscillate at (relative to the direction of the wave)?

Answer 1

90 degrees

Question 2

What speed do electromagnetic waves travel at? (and what is this the same as)

Answer 2

3 x 10 ^8 m/s

• same as speed of light

Question 3

name two sources of electromagnetic waves

Answer 3

microwave, sun

Question 4

what is the equation to calculate the frequency of a wave?

and what is the unit

Answer 4

wave speed
—————
wavelength

(Hz)

Question 5

State 2 uses of radio waves

Answer 5

• TV signals
• FM and AM radio broadcasts

Question 6

State uses of micro waves

Answer 6

• to heat up food in the microwave
• communication (WiFi, mobile phones, satellites)

Question 7

State uses of infrared waves

Answer 7

• Remote controls
• fibre optic communication
• thermal imaging

Question 8

State a use of visible light

Answer 8

• morse code in ships
• for photography

Question 9

State uses of ultraviolet waves (just remember 2)

Answer 9

• to detect forged bank notes
• fluorescent bulbs
• sterilises water (kills bacteria)
• can be used for suntans

Question 10

State uses of X-ray

Answer 10

• used for X-rays
• can kill skin cancer or other skin cells
• used for airport security

Question 11

State uses of gamma rays

Answer 11

• can kill cancer cells
• can sterilise medical instruments

Question 12

Are ultraviolet rays dangerous, and if so why?

Answer 12

YES

• can damage DNA in cells (grow very rapidly and cause skin cancer)
• if eyes exposed, cataracts can develop (make corneas cloudy)

Question 13

Are X-rays dangerous and if so why?

Answer 13

• can damage cells

- can cause cancer

Question 14

Are gamma rays dangerous and if so why?

Answer 14

• can damage cells in body

- leads to cancer

Question 15

Name the group of the electromagnetic spectrum used to kill cancer cells.

Answer 15

gamma rays or x-rays

Question 16

Describe the nature of an electromagnetic wave

Answer 16

• oscillate at a right angle/90 degrees to the wave’s direction.
• wave pointing up = magnetic field
• wave pointing sideways = electric field
• it is a transverse wave

Question 17

Describe why bones show up white on the X-ray film

Answer 17

• Bones absorb X-rays

Question 18

When radiographers operate X-ray machines, they stand behind lead screens. The screens absorb X-rays and prevent the operators from being repeatedly exposed to radiation.
Explain why this is a necessary precaution.

Answer 18

X-rays / gamma rays can damage DNA / are harmful to cells

Question 19

what kind of waves are electromagnetic waves?

Answer 19

transverse waves

Question 20

what is the relationship between frequency and wavelength across the electromagnetic spectrum

Answer 20

the greater the frequency, the smaller the wavelength

Question 21

what are our eyes sensitive to?

Answer 21

only visible light, not absorbed by the atmosphere

Question 22

can electromagnet waves travel through a vacuum?

and why

Answer 22

yes!

• as they are emitted from the sun and travel to the earth through SPACE
• remember space is a vacuum

Question 23

describe the difference between a longitudinal and transverse wave

Answer 23

• in a longitudinal wave, oscillations occur parallel to the direction of energy transfer
• in a transverse wave, oscillations occur perpendicular to the direction of energy transfer

Question 24

mnemonic to remember electromagnetic spectrum

Answer 24

Reptiles
Make
Interesting
Voices
Under
X-treme
Gold