P13 - Electromagnetic spectrum

Question 1

electromagnetic waves

Answer 1

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

Question 2

electromagnetic waves - energy transferred depends on

Answer 2

wavelength of waves

Question 3

Electromagnetic spectrum - starting from longest

Answer 3

radio
microwaves
infrared
visible light
UV radiation
X rays
Gamma radiation

Question 4

electromagnetic speed

Answer 4

3 hundred million m/s

Question 5

wave speed formula

Answer 5

frequency x wavelength

Question 6

human eye can only detect

Answer 6

visible light
-400nm to 700nm

Question 7

white light produced from

Answer 7

sun
ordinary lamps

Question 8

white light

Answer 8

all colours of visible spectrum

Question 9

wavelength of colours

Answer 9

increases from violet to red

Question 10

hotter an object =

Answer 10

more infrared it emits

Question 11

infrared absorbed by skin can

Answer 11

burn
kill skin cells as it heats them

Question 12

Infrared devices eg

Answer 12

-optical fibres in communication systems

Question 13

optical fibres in communication systems purpose

Answer 13

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

Question 14

microwaves

Answer 14

shorter wavelength than radio

Question 15

microwaves use

Answer 15

-carry satellite tv programmes + phone calls
-heat food

Question 16

how do microwaves heat food

Answer 16

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

Question 17

radio waves

Answer 17

• used for radio or tv broadcasting
  phone calls

Question 18

mobile phone radiation is

Answer 18

microwaves
near - microwave radio waves

Question 19

microwaves can heat

Answer 19

internal parts of body

Question 20

infrared use

Answer 20

heaters
food
cameras

Question 21

visible light use

Answer 21

fibre optic communications

Question 22

x rays and gamma eg

Answer 22

medical imaging
treatments

Question 22

uv use

Answer 22

energy efficient lamps
-tanning beds

Question 23

carrier waves

Answer 23

waves used to carry any type of signal

Question 24

carrier waves eg

Answer 24

between phone and nearby phone mast

Question 25

carrier waves type

Answer 25

can be radio microwaves infrared visible

Question 26

carrier waves type depends on

Answer 26

how much info in signal and distance to travel

Question 27

shorter wavelength carrier waves means=

Answer 27

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

Question 28

mobile phones safety?

Answer 28

research is needed to evaluate this

Question 29

carrier waves will (amplitude)

Answer 29

vary amplitude to carry signals

Question 30

Radio station process

Answer 30

-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

Question 31

AC

Answer 31

audio signal

Question 32

audio signals to transmitter to

Answer 32

modulate (vary) carrier waves

Question 33

varying ac to aerial

Answer 33

-causes it to emit radio waves to carry audio signal

Question 34

frequency of oscillations

Answer 34

frequency of radio waves

Question 35

optical fibres are

Answer 35

-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

Question 36

optical fibres use

Answer 36

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

Question 37

why does optical fibres carry more info than radio

Answer 37

light has a shorter wavelength =more pulses of waves

Question 38

UV properties

Answer 38

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

Question 39

X rays and gamma - penetration

Answer 39

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

Question 40

x rays and gamma properties

Answer 40

- short end of wavelength EM spectrum - carry much more energy per sec

Question 41

x rays produced when

Answer 41

electrons moving at high speeds are stopped

Question 42

Gamma rays produced by

Answer 42

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

Question 43

x ray uses

Answer 43

medical to make x ray images

Question 44

gamma use

Answer 44

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

Question 45

x rays and gamma - ionising power

Answer 45

- high - can cause mutations on living tissue (cancer) - makes uncharged atoms charged

Question 46

How x rays work

Answer 46

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

Question 47

what absorbs x rays

Answer 47

-bones - teeth - metal objects

Question 48

how is a radiograph made

Answer 48

- 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

Question 49

contrast medium for x rays of soft tissue

Answer 49

- barium compound - good absorber

Question 50

lead in x rays

Answer 50

prevents x rays from reaching other body parts

Question 51

flat panel detector

Answer 51

small screen - charge coupled devices - CCD

Question 52

CCD sensors in CCD

Answer 52

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

Question 53

radiation dose

Answer 53

-measure damage done to their body by ionising radiations

Question 54

radiation dose depends on

Answer 54

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

Question 55

radiation dose is measured in

Answer 55

sievers Sv or msv

Question 56

high radiation dose

Answer 56

kills living cells

Question 57

low radiation dose

Answer 57

gene mutation = cancer

Question 58

x ray therapy

Answer 58

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

Question 59

x ray in therapy

Answer 59

- shorter in wavelength - higher frequency - more energy

Question 60

x ray in imaging

Answer 60

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