Chapter 12 - Using Waves

Question 1

How do waves at one end of the EM spectrum differ from waves at the other end? (2 marks)

Answer 1

• One end is high frequency, short wavelength - Other end is low frequency, long wavelength

Question 2

What 4 properties do all waves have? (4 marks)

Answer 2

• All transfer energy - All transverse waves - Travel at the speed of light in a vacuum - All can be reflected, refracted and diffracted

Question 3

Radio waves have the ……. wavelength in the EM spectrum (1 mark)

Answer 3

Longest, meaning low frequency

Question 4

How are radio waves used in TV and FM radio (3 marks)

Answer 4

• Given out by a transmitter - As they cross an aerial, they are detected and info they carry can be received - TV and FM radio use radio waves with short wavelengths to carry their signals

Question 5

What are the sources and detectors for radio waves (2 marks)

Answer 5

Sources - Radio and TV transmitters Detectors - Radio and TV aerials

Question 6

Microwaves have a …. wavelength and a … frequency (2 marks)

Answer 6

• Long - Low

Question 7

How do microwaves heat food (5 marks)

Answer 7

• Special electrical circuits produce microwaves - Metal guides direct microwaves towards a rotating reflector - This reflector sends microwaves in all directions - Microwaves are reflected from metal casing - Food absorbs microwaves and becomes hot

Question 8

Two uses of microwaves (4 marks)

Answer 8

• Cooking : microwaves are used as food absorbs microwaves and becomes hot - Phones : messages sent to and from mobile phones are also carried by microwaves

Question 9

What are the sources and detectors for microwaves (2 marks)

Answer 9

Sources - microwave transmitters and ovens Detectors - microwave receivers

Question 10

Describe two differences between X-rays and visible light (2 marks)

Answer 10

• X-rays have shorter wavelength - X-rays have higher frequency

Question 11

State the name of the type of wave that includes X-rays and visible light

Answer 11

electromagnetic

Question 12

Which of the following is NOT a medical use of X-rays? A - Pre-natal scanning B - CT scans C - Killing Cancer Cells

Answer 12

A - Pre-natal scanning

Question 13

True or false? X-rays can be used to diagnose dental problems.

Answer 13

True

Question 14

Are X-rays absorbed or transmitted by metal?

Answer 14

absorbed

Question 15

True or false? X-rays can be used to break up kidney stones.

Answer 15

False

Question 16

EM SPECTRUM ACRONYM

Answer 16

Raging

Martians

Invaded

Venus

Using

X-ray

Guns

Question 17

A microwave cooker is often said to ‘cook the food from the inside’

Explain whether this statement is true by describing how energy is transferred to heat up all of the potato [3 marks]

Answer 17

• Microwaves are electromagnetic waves
• They cause water molecules to vibrate more / heat water
• Conduction through the rest of the potato

Question 18

Answer 18

• Electromagnetic induction
• Coil creates magnetic field around it
• Which cuts through the metal pan
• Inducing a voltage in the pan;
• Causing a current in the pan
• Current makes the pan get hot
• Which heats the water by conduction
• Water convects energy to potato;

Question 19

Suggest a property of radio waves that makes them suitable for use in communication [1 mark]

Answer 19

Can travel long distances

Question 20

Describe a possible harmful effect on people of microwaves [1 marks]

Answer 20

heating

Question 21

Describe a use of ultraviolet rays [1 marks]

Answer 21

kill bacteria

Question 22

Possible harmful effect on people of ultraviolet rays [1 marks]

Answer 22

skin cancer

Question 23

Explain what is meant by a digital signal [2 marks]

Answer 23

• Signal has two values

-

Question 24

Suggest two ways that this signal could be made to carry more information [2 marks]

Answer 24

• Increased frequency of wave
• using increased bandwidth;

Question 25

Answer 25

C

Question 26

Answer 26

A

Question 27

Answer 27

C

Question 28

Gamma radiation is used in hospitals even though it can be dangerous. Describe one use of gamma radiation in hospitals. | (2)

Answer 28

- sterilising medical equipment; gamma kills bacteria; - treating cancer/mutates cancer cells; radiotherapy/focused gamma rays; - detecting cancer; PET scanner/(radioactive) tracers/gamma camera;

Question 29

Explain the risks to patients and doctors of using gamma radiation. (2)

Answer 29

- increased risk of cancer/mutation of cells damage to neighbouring/good/healthy cells - radiation is ionising gamma has high/highest energy - patient is only exposed for a short period of time doctor has continual (low level) exposure

Question 30

State one way of reducing the risks to a doctor who uses gamma radiation. (1)

Answer 30

- (use for a) limited time - idea of working at a distance/in another room