P13- Electromagnetic waves

Question 1

Electromagnetic waves 4 properties?

Answer 1

Transverse waves
Transfer energy
Travel through a vacuum
All travel at same speed (speed of light)

Question 2

Electromagnetic waves fact about frequency and wavelength?

Answer 2

As they all travel at the same speed,
-if frequency increases, wavelength decreases
-if frequency decreases, wavelength increases

Question 3

Order of electromagnetic spectrum and pneumonic?

Answer 3

Gamma ray-> X ray-> Ultraviolet-> Visible-> Infrared-> Microwave-> Radio
Gammon x-rays use vibrant red micro radios

Question 4

Which electromagnetic waves have shorter wavelengths?
Their frequency, energy, danger and penetrating?

Answer 4

Gamma and X-rays.
Shorter wavelength
Higher frequency
Higher energy
More dangerous
More penetrating

Question 5

White light
Type of wave?
Found in?
Contains?
How to see it?

Answer 5

Electromagnetic
Sunlight
All the colours of the visible spectrum
Rainbow or glass prism

Question 6

Dif between colours of light?
From violet to red it..?

Answer 6

Different wavelengths /frequencies
Wavelength increases

Question 7

Absorption and emission of infrared radiation practical

Answer 7

Fill a shiny silver can and a matte black can with 200ml water straight from kettle and add a lid. Record initial temp and start the stopwatch. Record the temp of water every minute. After 5 mins calculate the total temp change. The silver can should have the least change due to radiation back into the water.

Question 8

Radio waves
Uses?
Dangers?

Answer 8

Radio, TV, mobile phone
Can cause internal heating in the body

Question 9

Microwave
Uses?
Dangers?

Answer 9

Heat up food, satellite signals
Can be absorbed by body cells

Question 10

Infrared waves
Uses?
Dangers?

Answer 10

Remote control for TV, electric heaters
Eye damage form bright light

Question 11

Visible waves
Uses?
Dangers?

Answer 11

Cameras to take photos
Eye damage from bright light

Question 12

Ultraviolet waves
Uses?
Dangers?

Answer 12

Sunbeds, sterilise medical equipment
Skin cancer, blindness

Question 13

X rays
Uses?
Dangers?

Answer 13

Identify broken bones, kill cancerous cells
High dose can kill living body cells

Question 14

Gamma rays
Uses?
Dangers?

Answer 14

Kill bacteria in food, sterilise medical equipment
High does can kill living body cells

Question 15

Infrared radiation
Emitted by?
Heat affecting the amount emitted?
Effect on the body?

Answer 15

All objects
Hotter the object, more infrared radiation it emits
Absorbed by the skin, can damage body cells

Question 16

Carrier waves

Answer 16

Waves used to carry any type of signal

Question 17

How are radio waves divided?
What 3 things does this affect?

Answer 17

Into groups based on their wavelength and frequencies.
How far they travel, how much they spread, how much info they carry

Question 18

Shorter radio wavelengths..
Info?
Range?
Spread out?

Answer 18

More info
Shorter distance travelled
Spread out less

Question 19

Shorter radio waves used for and why?
Longer radio waves used for and why?
Even longer radio waves used for and why?

Answer 19

Tv signals-> carry more info
Local radio stations-> greater range, not huge
National radio stations-> large range

Question 20

Shorter radio wavelengths around Earth?
Larger radio wavelengths around Earth?

Answer 20

Reflect of the outer atmosphere of Earth (ionosphere)

Diffract (bend) around Earth

Question 21

Mobile phones
Emits?
Causes?

Answer 21

Radio signals
May affect the brain when close, need more research

Question 22

How are signals transmitted and detected?

Answer 22

Transmitter: Produces alternating current, causes electrons to oscillate, produces carrier waves
Receiver: Carrier waves absorbed by electrons in antenna, causes them to oscillate, produces alternating current at same frequency as carrier waves produced from transmitter.

Question 23

Optical fibres
Transport?
Use?
Key feature?
How are the waves reflected and what is it called?

Answer 23

Signals, light or infrared radiation
Flexible
Visible light/infrared reflects off the inside of the optical fibre and
cannot escape.
Total internal reflection.

Question 24

Optical fibres
Info?
Security?

Answer 24

Carry more info than radio or microwaves, due to shorter wavelengths
More secure as signals stay in the fibre

Question 25

Ionisation

Answer 25

The process of making uncharged atoms become ions

Question 26

2 Types of EM waves that cause ionisation and how?

Answer 26

Gamma and X-rays
As they pass through substances, can knock electrons out of atoms so they become charged

Question 27

Ionisation effect on living cells?

Answer 27

Can cause the cell to die or mutate

Question 28

3 Effects of lower doses of ionisation in humans

Answer 28

Radiation can ionise DNA, which damages it
Can cause mutations
Can make cells reproduce rapidly (i.e. cancer)

Question 29

3 Effects of higher doses of ionisation in humans

Answer 29

Radiation can ionise DNA, which leads to cell death
Can then cause radiation burns or sickness
Very useful if want to kill the cell e.g. radiotherapy

Question 30

3 Ways for people working with X-rays to be protected?

Answer 30

Film badge which monitors level of radiation
Lead apron
Standing behind a screen

Question 31

How do X-ray machines work?
Dark and light areas?

Answer 31

X-ray machine produces x-rays at patient. Flat-panel detector placed beneath patient.
Rays pass through softer parts like tissue, show up as darker areas. Rays are absorbed by denser parts like bones, show up as lighter areas.

Question 32

What is a flat-panel detector and what does it do?

Answer 32

A small screen that contains a charge-coupled device (CCD). This converts X-rays to light, so a computer to display a X-ray image

Question 33

How to see an organ on an X-ray?

Answer 33

Use a contrast medium in the organ, eg eating a substance that absorbs X-rays to see the inside of a stomach

Question 34

3 things that affect the radiation dose?
What is it measured in?

Answer 34

Type of radiation
Length of exposure
Rate of absorption from body
Sieverts (Sv)