P12

Question 1

Shortest wavelength in the EM spectrum

Answer 1

Gamma rays

Question 2

Longest wavelength in the EM spectrum

Answer 2

Radio waves

Question 3

Use of radio waves

Answer 3

Connect TV, radios and phone signals

Question 4

Uses of microwaves

Answer 4

Used for communication, carry mobile phone signals and can heat food quicker

Question 5

How do microwaves heat food

Answer 5

Penetrate into food and are absorbed by the water molecules in the food and then they heat the food

Question 6

Use of infared radiation

Answer 6

Remote control handset for the tv and video equipment

Question 7

Use of infared radiation in medicine

Answer 7

Infared scanners used in medicine to detect infared radation emmited from hot spots on the body surface. These hot areas can mean the tissue underneath is unhealthy

Question 8

Uses of light

Answer 8

Film camera (light is focused by the camera lens on to a light sensitive film)
Digital camera or a mobile phone camera, the light is focused by the lens on to a sensor

Question 9

What are carrier waves

Answer 9

Waves used to carry any type of signal

Question 10

What are optical fibres

Answer 10

Very thin transparent fibres that are used to transmit communication signals by light and infared radiation

Question 11

How are ultraviolet waves harmful to us

Answer 11

Harmful to human eyes as can cause blindness and also harmful to your skin as can cause burn

Question 12

Where do ultraviolet waves lie on the EM spectrum

Answer 12

Between violet light and x rays

Question 13

Properties of x rays and gamma rays

Answer 13

Short wavelength
Carry much more energy per second than longer wavelentghs

Question 14

How are x rays and gamma rays different

Answer 14

• x rays produced when electrons or other particles moving at high speeds are stopped
• gamma rays are produced by radioactive substance
• gamma rays have shorter wavelength that x rays so they can penetrate substances more than x rays

Question 15

2 key uses of high energy gamma rays

Answer 15

Killing harmful bacteria and killing cancer cells

Question 16

Microwave ovens:

Answer 16

Energy is transferred from a microwave source to the food in the oven, heating it

Question 17

Radiant heaters:

Answer 17

Infrared radiation transfer energy from the heater to heat the surroundings

Question 18

How do carrier waves carry information:

Answer 18

They vary their amplitude

Question 19

How are X-rays used in hospitals?

Answer 19

-to make images of your internal body parts
-to destroy tumours at or near the body surface

Question 20

Problems with x-rays:

Answer 20

Ionising radiation so can damage living tissues when passing through

Question 21

How are x-rays absorbed?

Answer 21

By bones and teeth

Question 22

Visible light:

Answer 22

-Wavelength ranges from 400nm-700nm
-human eye can detect visible light

Question 23

White light

Answer 23

Light from ordinary lamps and from the sun

Question 24

Radiowave range

Answer 24

300000Hz to 3000 million Hz

Question 25

The shorter the wavelength of the waves:

Answer 25

-the more info they carry
-the shorter their range
-the less soread out

Question 26

What happens when you speak?

Answer 26

You produce sound waves of different frequencies

Question 27

How is signal in a microphone transmitted and detected?

Answer 27

1) an oscillator supplies carrier waves to the transmitter in the form of an altering current

2) audio signal is supplied to transmitter and modulates the carrier waves

3) these waves are supplied to the transmitter aerial, causing it to emit radio waves

4) they induce alternating current which causes oscillations

5) the reciever curcuit seperates the audio signal from the carrier waves, supplied to a loud speaker which then sends sound waves that are recieved by the microwave