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GCSE AQA Physics > P13 - Electromagnetic spectrum > Flashcards

P13 - Electromagnetic spectrum Flashcards

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1
Q

electromagnetic waves

A

electric and magnetic disturbances
- can be used to transfer energy
- from a source to an absorber
-don’t transfer matter

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2
Q

electromagnetic waves - energy transferred depends on

A

wavelength of waves

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3
Q

Electromagnetic spectrum - starting from longest

A

radio
microwaves
infrared
visible light
UV radiation
X rays
Gamma radiation

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4
Q

electromagnetic speed

A

3 hundred million m/s

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5
Q

wave speed formula

A

frequency x wavelength

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6
Q

human eye can only detect

A

visible light
-400nm to 700nm

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7
Q

white light produced from

A

sun
ordinary lamps

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8
Q

white light

A

all colours of visible spectrum

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9
Q

wavelength of colours

A

increases from violet to red

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10
Q

hotter an object =

A

more infrared it emits

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11
Q

infrared absorbed by skin can

A

burn
kill skin cells as it heats them

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12
Q

Infrared devices eg

A

-optical fibres in communication systems

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13
Q

optical fibres in communication systems purpose

A
  • will carry signals from remote control handsets + inside optical fibres
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14
Q

microwaves

A

shorter wavelength than radio

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15
Q

microwaves use

A

-carry satellite tv programmes + phone calls
-heat food

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16
Q

how do microwaves heat food

A

-penetrating food
-absorbed by water molecules
-the microwave doesn’t become hot as it hasn’t got water molecules to absorb the heat

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17
Q

radio waves

A
  • used for radio or tv broadcasting
    phone calls
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18
Q

mobile phone radiation is

A

microwaves
near - microwave radio waves

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19
Q

microwaves can heat

A

internal parts of body

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20
Q

infrared use

A

heaters
food
cameras

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21
Q

visible light use

A

fibre optic communications

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22
Q

x rays and gamma eg

A

medical imaging
treatments

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22
Q

uv use

A

energy efficient lamps
-tanning beds

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23
Q

carrier waves

A

waves used to carry any type of signal

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24
Q

carrier waves eg

A

between phone and nearby phone mast

25
Q

carrier waves type

A

can be radio
microwaves
infrared
visible

26
Q

carrier waves type depends on

A

how much info in signal
and distance to travel

27
Q

shorter wavelength carrier waves means=

A

more info can be carried
-shorter their range
- less they spread out

28
Q

mobile phones safety?

A

research is needed to evaluate this

29
Q

carrier waves will (amplitude)

A

vary amplitude to carry signals

30
Q

Radio station process

A

-microphone produces AC when sound waves reach it
- oscillator supplies carrier waves to transmitter as AC
- modulated carrier waves are supplied to transmitter aerial
- emits radio waves
- absorbed by receiver aerial = induces AC
- causes oscillations in receiver
- receiver circuit separates audio signal from carrier waves
- supplied to loudspeaker which sends out sound waves

31
Q

AC

A

audio signal

32
Q

audio signals to transmitter to

A

modulate (vary) carrier waves

33
Q

varying ac to aerial

A

-causes it to emit radio waves to carry audio signal

34
Q

frequency of oscillations

A

frequency of radio waves

35
Q

optical fibres are

A

-thin glass fibres
- transmits signal carried by light/infrared
- light cannot escape the fibre
- when they reach the surface = they are reflected back into it

36
Q

optical fibres use

A

-carry more info than microwaves/radio
- more secure as signals stay in fibre

37
Q

why does optical fibres carry more info than radio

A

light has a shorter wavelength
=more pulses of waves

38
Q

UV properties

A

shorter wavelength than visible light
-carries more enrgy
- can harm skin/ eyes (cancer or blindness)

39
Q

X rays and gamma - penetration

A

can travel though substances if not too dense
-stopped by thick lead plates

40
Q

x rays and gamma properties

A
  • short end of wavelength EM spectrum
  • carry much more energy per sec
41
Q

x rays produced when

A

electrons moving at high speeds are stopped

42
Q

Gamma rays produced by

A

radioactive substances when unstable nuclei release energy
- shorter wl than x ray so will penertrate more

43
Q

x ray uses

A

medical to make x ray images

44
Q

gamma use

A

-kills bacteria in food
- kills bacteria on surgical instruments
- kills cancer cells

45
Q

x rays and gamma - ionising power

A
  • high
  • can cause mutations on living tissue (cancer)
  • makes uncharged atoms charged
46
Q

How x rays work

A
  • x rays from a tube are directed onto patient
  • light-proof cassette contains photographic film or a flat panel on other side of patient
47
Q

what absorbs x rays

A

-bones
- teeth
- metal objects

48
Q

how is a radiograph made

A
  • x rays pass through soft tissue
  • bone absorbs x ray so it appears lighter
  • cavity in tooth appears darker
  • soft tissue organs can be filled with a contrats medium to absorb x ray easier
49
Q

contrast medium for x rays of soft tissue

A
  • barium compound
  • good absorber
50
Q

lead in x rays

A

prevents x rays from reaching other body parts

51
Q

flat panel detector

A

small screen
- charge coupled devices
- CCD

52
Q

CCD sensors in CCD

A

convert x rays to light
-light to electric signal
- sent to computer = image

53
Q

radiation dose

A

-measure damage done to their body by ionising radiations

54
Q

radiation dose depends on

A

-type
- time body has been exposed to
- energy per second absorbed by body

55
Q

radiation dose is measured in

A

sievers
Sv
or msv

56
Q

high radiation dose

A

kills living cells

57
Q

low radiation dose

A

gene mutation = cancer

58
Q

x ray therapy

A

destroys cancerous tumours in body
- thick plates stop from reaching other body parts
- the gap where the tumour is

59
Q

x ray in therapy

A
  • shorter in wavelength
  • higher frequency
  • more energy
60
Q

x ray in imaging

A
  • longer wavelength
  • lower energy to be absorbed by bones
    -not enough to destroy tumours

GCSE AQA Physics (37 decks)

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