P13 Electromagnetic waves

Question 1

RMIVUXG
is in order of what

Answer 1

order of highest to lowest wavelength
and lowest to highest energy and frequency

Question 2

relationship between energy, frequency and wavelength of a wave

Answer 2

the higher the wavelength
the lower the energy and frequency

Question 3

RMIVUXG =

Answer 3

radio waves
microwaves
infrared
visible light
ultraviolet
x rays
gamma

Question 4

range wavelengths visible to humans

Answer 4

400nm to roughly 700nm

Question 5

mgr do electromagnetic waves transfer and not transfer

Answer 5

transfer energy
not matter

Question 6

what is white light

Answer 6

light containing all the colours of the visible light spectrum

Question 7

how does infrared radiation affect skin cells?

Answer 7

• skin cells absorb infrared,
• which can damage, burn and kill them by heating them.

Question 8

why do optical fibres often use infrared radiation rather than visible light?

Answer 8

it is absorbed less by the glass fibres than visible light

Question 9

uses of radio waves

Answer 9

television and radio

Question 10

uses of microwaves

Answer 10

heating food, satellite communications

Question 11

how do microwaves heat food

Answer 11

• microwaves penetrate food,
• water molecules in the food absorb the microwaves, heating the food.

Question 12

how can microwaves and radio waves be dangerous to humans?

Answer 12

dangerous as they penetrate people’s bodies
and heat their internal parts

Question 13

what are carrier waves
how are they suited to their function

Answer 13

waves that carry any type of signal
they carry information by varying their amplitude

Question 14

how does the length of a wave relate to:
- the amount of information it carries,
- its range,
- how much it spreads out.

Answer 14

the shorter the wave:
- the more information it carries,
- the shorter its range,
- the less it spreads out.

Question 15

what doing optical fibres do

Answer 15

transmit signals carried by light or infrared radiation

Question 16

how are optical fibres suited for their purpose:

Answer 16

• signals stay in the fibres because they reflect off the surfaces,
• carry lots of information due to short wavelength.

Question 17

how can ultraviolet radiation be dangerous to humans

Answer 17

can cause:
- blindness,
- sunburn and skin cancer

Question 18

differences between ultraviolet and x ray radiation

Answer 18

• x rays caused by electrons/particles moving at very high speeds being stopped
  while gamma rays are caused by unstable nuclei releasing energy,
• gamma rays have shorter wavelengths than x rays (so carry more information and transfer more energy).

Question 19

how does the density of an object relate to how many X rays it absorbs

Answer 19

the denser an object
the more X rays it absorbs

Question 20

2 uses of gamma rays

Answer 20

• killing harmful bacteria,
• killing cancer cells

Question 21

2 examples of ionising radiation

Answer 21

X rays
gamma radiation

Question 22

how to prevent harm from ultraviolet radiation

Answer 22

• wear skin creams,
• do not exceed the recommended time in sunbeds,
• wear goggles in sunbeds.

Question 23

describe how X rays form a negative image

Answer 23

• X ray tube turns on and X rays are sent to body part,
• hard materials like bone and metal absorb X rays, making those areas light,
• X rays pass through soft materials like organs and tissues and reach the detector, making it dark,
• CCD converts X rays to light,
• light rays create electronic signals which display a digital image.

Question 24

what is a contrast medium used for in X ray imaging?

Answer 24

to fill soft tissue so that it can absorb X rays
so that area will appear light and its internal surfaces visible on the digital image.

Question 25

what is radiation dose a measure of?

Answer 25

a measure of the damage done to a person’s body due to ionising radiation

Question 26

what does radiation does depend on?

Answer 26

• the type of radiation,
• how long one is exposed to the radiation,
• the amount of energy absorbed by the body per second.

Question 27

unit of radiation dose

Answer 27

Sv
1Sv = 1000Sv

Question 28

background sources of ionising radiation

Answer 28

cosmos radiation
radon gas

Question 29

what are lead plates for in X ray imaging?

Answer 29

stop X rays reaching other parts of the body

Question 30

compare the X rays used for imaging
with the X rays used for killing cancerous tumours

Answer 30

X rays for imaging are low energy as they are absorbed by bones but can pass through soft tissues and organs

X rays for killing cancerous tumours are higher energy as low energy would not be able to kill cancerous cells

Question 31

uses of infrared radiation

Answer 31

optical fibres, infrared cameras, electrical heaters

Question 32

uses of visible light

Answer 32

fibre optic communication

Question 33

uses of ultraviolet

Answer 33

sunbeds, energy efficient lamps