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Physics P1-P5 > P5.2 - Electromagnetic Fields > Flashcards

P5.2 - Electromagnetic Fields Flashcards

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1
Q

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

A

90 degrees

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2
Q

electromagnetic waves all have …….. ………..

A

the same velocity

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3
Q

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

A

3 x 10 ^8 m/s

  • same as speed of light
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4
Q

name two sources of electromagnetic waves

A

microwave, sun

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5
Q

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

and what is the unit

A

wave speed
—————
wavelength

(Hz)

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6
Q

State 2 uses of radio waves

A
  • TV signals

- Used to transfer information (ie. between phones and satellites)

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7
Q

State uses of micro waves,3

A
  • to heat up food in the microwave
  • communicate with satellites
  • WiFi and bluetooth signals
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8
Q

State uses of infrared waves, 4

A
  • Remote controls
  • used in optical fibres
  • cooks food in oven or grill
  • radiator transfers energy to thermal store
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9
Q

State a use of visible light

A
  • morse code in ships

- for photography

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10
Q

State uses of ultraviolet waves, 5

A
  • helps produce vitamin d
  • bodily fluids glow in ultraviolet rays (ie. in crime scenes)
  • to detect forged bank notes
  • sterilises water (kills bacteria)
  • can be used for suntans
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11
Q

State uses of X-ray, 3

A
  • used for X-rays
  • can kill skin cancer or other skin cells
  • used for airport security
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12
Q

State uses of gamma rays, 4

A
  • can kill cancer cells
  • can kill bacteria in food
  • can kill people
  • can find leaks in underground pipes
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13
Q

Are ultraviolet rays dangerous, and if so why?

A

YES

  • can damage DNA in cells (grow very rapidly and cause skin cancer)
  • if eyes exposed, cataracts can develop (make corneas cloudy)
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14
Q

Are X-rays dangerous and if so why?

A
  • can damage cells

- can cause cancer

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15
Q

Are gamma rays dangerous and if so why?

A
  • can damage cells in body

- can kill cells in body

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16
Q

State a source of infrared rays

A

remote controls

17
Q

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

A

gamma rays or x-rays

18
Q

Describe the nature of an electromagnetic wave

A
  • oscillate at a right angle/90 degrees to the wave’s direction.
  • wave pointing up = electric field
  • wave pointing sideways = magnetic field
  • it is a transverse wave
19
Q

Suggest a control variable for an experiment investigating various rays of the electromagnetic spectrum

A
  • keep the same intensity of Electromagnetic radiation
20
Q

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

A
  • Bones absorb X-rays
  • photographic film darkens when it absorbs X-rays
  • X-rays pass through soft tissues (such as skin and muscle)
21
Q

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.
Why this is a necessary precaution.

A

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

22
Q

what kind of waves are electromagnetic waves?

A

transverse waves

23
Q

what do electromagnetic waves transfer?

A

energy from sources to absorbers

24
Q

state examples of where electromagnetics transfer waves from sources to absorbers
(and describe what happens to the absorbers because of it)

A

microwave emits electromagnetic waves -> skin absorbs infrared waves

or “ -> food absorbs microwave radiation

  • THEY BOTH HEAT UP
25
Q

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

A

the greater the frequency, the smaller the wavelength

26
Q

what are our eyes sensitive to?

A

only visible light, not absorbed by the atmosphere

27
Q

can electromagnet waves travel through a vacuum?

and why

A

yes!

  • as they are emitted from the sun and travel to the earth through SPACE
  • remember space is a vacuum
28
Q

describe the difference between a longitudinal and transverse wave

A
  • 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

Physics P1-P5 (14 decks)

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