Topic 6 Em Waves And Rheur Uses

Question 1

What are microwaves used by

Answer 1

Satellite

Question 2

What does communication to and from satellites use

Answer 2

Microwave which can easily pass through the earths watery atmosphere

Question 3

For satellite TV where is the signal from the transmitter transmitted through

Answer 3

Through space

Question 4

What picks up the signals

Answer 4

Satellite receiver dish opting thousands of kilometres above earth satellite transmits a signal back to earth in a different direction

Question 5

Where is the signal from the satellite dish in space received

Answer 5

By satellite dish on the ground there is a slight time delay between single being sent and received because of the long distance the signal has a to travel

Question 6

What are the microwave is absorbed by in microwave ovens

Answer 6

Water molecules in the food

Question 7

The microwave penetrate up to a few centimetres into the food before doing what

Answer 7

Being absorbed and transferring energy that they’re carrying to the water molecules in the food cause in the water to heat up

Question 8

What are the water molecules do with the energy

Answer 8

Transfer this energy to the rest of the molecules in the food by heating

Question 9

What can infrared radiation be used for

Answer 9

To detect infrared or monitor temperature on infrared cameras

Question 10

What is infrared radiation given off by

Answer 10

Hot objects

Question 11

The hotter the object the

Answer 11

The more infrared radiation is given out

Question 12

What can infrared cameras be used for

Answer 12

Detect the IR radiation and turns it into an electrical signal which is displayed on the screen as a picture

Question 13

The hotter of the object is

Answer 13

The brighter it appears on the camera

Question 14

What does absorbing infrared radiation cause

Answer 14

Objects to get hotter

Question 15

What happens to the temperature of food as it absorbs infrared radiation

Answer 15

It increases

Question 16

What do electric heaters contain

Answer 16

How long piece of wire that heats up when I current flows through it

Question 17

What does the wires in electric heaters omit

Answer 17

Lots of infrared radiation
And a little visible light (the wire glows)

Question 18

What is the emitted radiation absorbed by

Answer 18

The objects on the air in the room

Question 19

What is energy transferred from the Ir waves to

Answer 19

The thermal energy stores of objects causing the temperature in to increase

Question 20

What are optical fibres

Answer 20

Thing glass or plastic fibres that carry data (from telephones or computers) over long distances as pulses of visible light

Question 21

How do optical fibres work

Answer 21

Because of reflection
The light rays are bounced back and forth until they reach the end of the fibre

Question 22

What em wave are used in optical fibres

Answer 22

Visible light

Question 23

What happens to the light as it travels along on the fibre

Answer 23

It isn’t easily absorbed or scattered

Question 24

What is fluorescence

Answer 24

A property of certain chemicals where uv radiation is absorbed and them visible light is emitted

Question 25

What do fluorescent lights generate

Answer 25

UV radiation which is absorbed and re emitted as visible light by a laye of a compound called a phosphor on the inside of a bulb
They are energy efficient so they’re good to use when light is needed for long periods

Question 26

Security pens can be used to mark property with your name and what happens under uv light

Answer 26

The ink will glow fluorescent but otherwise it is invisible
This can help identify property if it is stolen

Question 27

What can exposure to UV from the sun give u

Answer 27

A suntan

Question 28

What do uv lamps give people

Answer 28

An artificial sun tan

Question 29

Why can over exposure to uv be bad

Answer 29

Cause sun burn or skin cancer

Question 30

What do radiographers in hospitals do

Answer 30

Take X-ray photographs of people to see if they have broken bones

Question 31

How can X-rays give u an image

Answer 31

Pass easily through flesh but not easily through denser materials like metal or bone
So it is the amount of radiation absorbed or not absorbed that gives the image

Question 32

How do radiographers use x rays and gamma rays to treat people with cancer

Answer 32

Through radiotherapy
High doses of these rays kill all living cells so are directed towards the cancer cells to avoid killing to many normal healthy cells

Question 33

How can gamma rays be used as a medical tracer

Answer 33

Gamma emitting source is injected into the patient and its progress is followed around the body
Gamma radiation is well suited to this because it can pass our through the body to be detected

Question 34

What do radiographers wear to protect themselfs from exposure

Answer 34

Lead aprons and stand behind lead screen or leave room