Paper 1 - Waves

Question 1

What are the differences between digital and analogue signals?

Answer 1

• analogue is continuously varying
• digital has only discrete values
• digital is less prone to interference than analogue
• digital can be processed more easily than analogue by a computer

Question 2

What happens when a metal aerial absorbs radio waves?

Answer 2

• creates an alternating current
• with the same frequency as the radio wave

Question 3

What properties that all electromagnetic waves have?

Answer 3

• travel at the same speed in a vacuum
• can be refracted/reflected
• transfer energy
• can be absorbed

Question 4

What is the correct order of the electromagnetic spectrum?

Answer 4

Radio → Micro → Visible light → UV → X-Rays → Gamma

Question 5

Define amplitude`

Answer 5

The distance between a peak and an equilibrium

Question 6

Define wavelength

Answer 6

The distance from one point on a wave to the same spot on the next wave

Question 7

Define trough

Answer 7

The maximum value of downward displacement within a wave cycle

Question 8

Define crest

Answer 8

The maximum value of upward displacement within a wave cycle

Question 9

Give an example of longitudinal waves

Answer 9

• Sound waves
• Seismic P Waves

Question 10

What properties can be obtained from a displacement-velocity graph of a wave?

Answer 10

• Amplitude
• Frequency
• Wavelength
• Wave speed

Question 11

How does the direction of energy transfer relate to the direction of particle vibration in a transverse wave?

Answer 11

In a transverse wave, the direction of energy transfer is perpendicular to the direction of particle vibration

Question 12

How does the direction of energy transfer relate to the direction of particle vibration in a longitudinal wave?

Answer 12

In a longitudinal wave, t he direction of energy transfer is parallel to the direction of particle vibration

Question 13

Define compression

Answer 13

The point in a longitudinal wave cycle in which the particles are closest together

Question 14

What properties can be obtained from a displacement-time graph of a wave?

Answer 14

• Amplitude
• Frequency
• Time period
• Wavelength
• Wave speed

Question 15

Give an example of a transverse wave

Answer 15

• Electromagnetic waves
• S waves

Question 16

Define wavefront

Answer 16

A surface containing points affected in the same way by a wave at a given time.

Question 17

What do waves transfer and without what?

Answer 17

Waves transfer energy and information without transferring matter

Question 18

What is the relationship between = wave speed, frequency and wavelength?

Answer 18

v = f x λ

Question 19

What the relationship between frequency and time period?

Answer 19

f = 1 / t

Question 20

Why there is a change in the observed frequency and wavelength of a wave
when its source is moving relative to an observer?

Answer 20

• This is known as the doppler effect
• The wavelength gets shorter
• The frequency increases
• So the pitch increases

Question 21

What are radio waves used for?

Answer 21

Broadcasting and communications

Question 22

What are microwaves used for?

Answer 22

• Cooking
• Satellite transmissions

Question 23

What are infrared waves used for?

Answer 23

• Heaters
• Night vision equipment

Question 24

What are visible light rays used for?

Answer 24

• Optical fibres
• Photography

Question 25

What are ultraviolet rays used for?

Answer 25

Florescent lamps

Question 26

What are X-rays used for?

Answer 26

Observing the internal structure of objects and materials including for medical applications

Question 27

What are gamma rays used for?

Answer 27

- Sterilising food - Sterilising medical equipment - Destroying cancer cells

Question 28

What are the detrimental effects of excessive exposure of the human body to microwaves?

Answer 28

Internal heating of body tissue

Question 29

What are the detrimental effects of excessive exposure of the human body to infrared radiation?

Answer 29

Skin burns

Question 30

What are the detrimental effects of excessive exposure of the human body to ultraviolet rays ?

Answer 30

- Damage to surface cells - Blindness

Question 31

What are the detrimental effects of excessive exposure of the human body to gamma rays?

Answer 31

- Cancer - Mutation

Question 32

Describe simple protective measure against the risks

Answer 32

- Wear goggles - Wear gloves - Minimise exposure time - Maximise distance away from the electromagnetic wave

Question 33

Give 2 properties about light waves

Answer 33

- They are transverse - They can be reflected and refracted

Question 34

When does total internal reflection occur?

Answer 34

When the angle of incidence equals the angle of reflection

Question 35

What is the equation for refractive index?

Answer 35

n = sin i / sin r

Question 36

Describe the role of total internal reflection in transmitting information along optical fibres and in prisms

Answer 36

Total Internal Reflection is used to transmit signals along optical fibres

Question 37

Explain the meaning of critical angle c

Answer 37

The angle (specific to the medium) that, if the angle of incidence is equal to c, then the angle of refraction is 90°

Question 38

What is the equation for the critical angle

Answer 38

sin c = 1 / n

Question 39

Explain the path of a ray of light in an optical fibre

Answer 39

- Total internal reflection occurs - The core has a higher refractive index than air - Angle of incidence is greater than the critical angle - Light travels more slowly in glass

Question 40

What is a hazard of microwave radiation?

Answer 40

Internal heating of tissue

Question 41

State the name of an electromagnetic wave with a wavelength longer than microwave radiation

Answer 41

Radio