P13(Electromagnetic Waves)

Question 1

What are electromagnetic waves

Answer 1

Electromagnetic waves are electric and magnetic disturbances that can be used to transfer energy from a source to an absorber

Question 2

What is the electromagnetic spectrum made up of (in order of decreasing and increasing wavelength and energy)

Answer 2

-radio waves
-microwaves
-infrared radiation
-visible light
-ultraviolet Waves
-X-rays and gamma rays

Question 3

White light contains…

Answer 3

All the colours of the visible spectrum

Question 4

What is infrared radiation used for

Answer 4

-remote control handsets
-medical equipment
-night vision

Question 5

What are microwaves used for

Answer 5

-communications
-microwave ovens

Question 6

What are radio waves used for

Answer 6

-communications
-to connect to wireless devices

Question 7

The shorter the wavelength of radio and microwaves …

Answer 7

-the more information they can carry
-the shorter their range
-the less they spread out

Question 8

What are carrier waves

Answer 8

-Waves that are used to carry information
-they do this by varying their amplitude

Question 9

How are signals transmitted and detected

Answer 9

-An oscillator supplies carrier waves to the transmitter in the form of an alternating current
-The audio signal is supplied to the transmitter where it’s used to modulate the carrier waves
-the modulated carrier waves from the transmitter are supplied to the transmitter aerial
-the varying alternating current supplied to the aerial causes it to emit radio waves that carry the audio signal
-when the radio waves are absorbed by a receiver aerial it causes oscillations in the receiver
-the receiver circuit separates the audio signal from the carrier waves

Question 10

What are optical fibres

Answer 10

Thin transparent fibres that are used to transmit communications signals by light and infrared radiation

Question 11

What are ultraviolet waves used for

Answer 11

Tanning beds

Question 12

What are the dangers of ultraviolet waves

Answer 12

-cause blindness
-harm the skin

Question 13

How are X rays produced

Answer 13

When electrons or other particles moving at high speeds are stopped

Question 14

How are gamma rays produced

Answer 14

Produced by Radioactive substances when unstable nuclei release energy

Question 15

What are X rays used for

Answer 15

Used in hospitals to make x ray images

Question 16

What are gamma rays used for

Answer 16

-killing harmful bacteria
-killing cancer cells

Question 17

X rays and gamma rays are highly …

Answer 17

Ionising

Question 18

X rays and gamma rays damage …

Answer 18

Living tissue when they pass through it

Question 19

High energy x rays are used for ..

Answer 19

Therapy

Question 20

Low energy X rays are suitable for imaging because…

Answer 20

-they are absorbed by bones and teeth
-but they pass through soft tissue and gaps such as cracks in bones