Electromagnetic Waves

Question 1

What types of waves are em waves

Answer 1

Transverse waves that transfer energy from a source to an absorber

Question 2

How do em waves travel and through what can they travel

Answer 2

They travel at the same speed as vibrations of electric and magnetic fields
Through air or a vacuum

Question 3

What are the 7 types em waves are grouped

Answer 3

Radio waves 
Microwaves 
Infra red 
Visible light 
Ultra violet 
X-rays 
Gamma rays 
Roman Men Invented Very Unusual X-ray Guns

Question 4

How is the em spectrum ordered from radio waves to gamma rays

Answer 4

It increases in frequency

It decreases in wavelength

Question 5

Why is there such a merge change in frequencies

Answer 5

Em waves are generated by a variety of changes in the atoms and their nuclei

Question 6

What currents are in electromagnetic wave s

Answer 6

Alternating currents as they are made up of oscillating charges and produce oscillating electric and magnetic fields

Question 7

How do you produce radio waves and what is the object called

Answer 7

Use an alternating current in a circuit

A transmitter makes charges oscillate to create a radio wave

Question 8

What happens to radio waves when they reach the receiver and to the electrons in the material of the receiver

Answer 8

The wave is absorbed and the energy is transferred to the electrons in the material of the receiver
This energy causes the electrons to oscillate and if the receiver is apart of a complete circuit it will generate an alternating current

Question 9

How long are radio waves wavelengths

Answer 9

Longer than 10cm

1m - 10*4 m

Question 10

How can long wave radio waves get around the world and over mountains

Answer 10

The wavelengths diffract around the curved surface of the earth and over mountains

Question 11

How are short wave radio waves still received at long distances from the transmitter

Answer 11

They are reflected from the ionosphere

Question 12

What’s the ionosphere

Answer 12

An electrically charged layer of the earths upper atmosphere

Question 13

What are the wavelengths of the radiowaves for tv and fm radio transmissions

Answer 13

They are very short wavelengths so you must be insight of a transmitter

Question 14

What waves are used for communication too and from satellites

Answer 14

Microwaves

Question 15

How are the wavelengths in microwave ovens and microwaves to satellites different

Answer 15

In microwaves oven the waves need to be absorbed by water molecules in food so they use a different wavelength

Question 16

What happens to the microwaves in microwave ovens

Answer 16

The microwaves penetrate up to a few cm in the food before being absorbed by the water molecules in the food and thy here transfer the energy they are carrying to heat up the water which passes heat through the rest of the food

Question 17

What are Infared cameras used for and how is this done

Answer 17

To detect infared radiation and monitor temperature
The camera detects ir radiation and turns it into an electrical signal to display on a screen
The hotter the object the brighter it appears

Question 18

What can Infared radiation be used for

Answer 18

Detecting or increasing temperature

Question 19

How does Infared radiation increase temperature

Answer 19

When an object absorbs IR radiation

Eg when cooking food

Question 20

How do electric heaters work

Answer 20

They contain a long piece of wire that heats up when a current flows through it
The wire will emit a lot of Infared radiation which will be absorbed by other objects and the air

Question 21

What are optical fibres

Answer 21

Thin glass or plastic fibres that can carry data over long distances as pulses of visible light

Question 22

How do fibre optic cables work

Answer 22

Through reflection
The light rays are bounced back and forth until the reach the end of the fibre
The light is not easily absorbed as it travels

Question 23

How are flourescent colours so bright

Answer 23

Fluorescence is a property of a certain chemical which absorbs ultraviolet and Emmits visible light

Question 24

Where’s is ultraviolet radiation used

Answer 24

Flourescent lights
Security pens
Suntans

Question 25

What waves are used in medicine

Answer 25

X-rays and gamma rays

Question 26

How do X-rays work to look at bones

Answer 26

The X-ray will easily pass though the flesh but both through the denser material of bones
So the amount of radiation that’s absorbed gives the the X-ray image

Question 27

How do radiographer uses X-rays and gamma rays to treat cancer

Answer 27

High doses of the waves can kill cancer cells

Question 28

How is gamma radiation used as a medical tracer

Answer 28

A gamma emmiting source is objected into a patient and followed around the body

Question 29

What waves and types can cause damage when passing though the body

Answer 29

Waves with high frequency like gamma X-rays and UV

As they transfer lots of energy

Question 30

How is UV radiation damaging

Answer 30

It damages surface cells and lead to sunburn

More seriously it can lead to skin cancer

Question 31

What can too much exposure to X-rays and gamma rays cause

Answer 31

Ionising radiation where the energy kicks off electrons in atoms
This causes gene mutation or cell destruction and cancer

Question 32

What is radiation dose

And what is it measured in

Answer 32

Measured in sieverts
Is a measure of the risk of harm of a body being exposed to radiation
Depends on total amount of radiation absorbed and how harmful the type of radiation is