P5

Question 1

What is a wave?

Answer 1

A wave is an oscillation that transfers energy

Question 2

What are longitudinal waves (+ e.g.)?

Answer 2

A longitudinal wave is a wave where the direction of vibration of individual air molecules is the same as the direction of the wave. An example is sound waves

Question 3

What are transverse waves (+e.g.)?

Answer 3

A transverse wave is a wave where the direction of vibration is at right angles to the direction of travel of the wave

Question 4

Draw a diagram of a longitudinal wave and label it

Answer 4

see p.g. 142

Question 5

Draw a diagram of a transverse wave and label it

Answer 5

see p.g. 142

Question 6

What is amplitude, what is its symbol and what is it measured in?

Answer 6

Amplitude is the distance from the middle to the top or bottom of a wave. Its symbol is A and it is measured in metres or volts.

Question 7

What is frequency, what is its symbol and what is it measured in?

Answer 7

Frequency is the number of waves per second. Its symbol is F and it is measured in Hz.

Question 8

What is wavelength, what is its symbol and what is it measured in?

Answer 8

Wavelength is the distance from one point on a wave to the same point on the next wave. its symbol is lambda and it is measured in m

Question 9

What is time period, what is its symbol and what is it measured in?

Answer 9

Time period is the time for one wave to pass a given point. its symbol is T and it is measured in seconds.

Question 10

Draw a time trace for a wave

Answer 10

see p.g. 143

Question 11

Draw a snapshot for a wave

Answer 11

see p.g. 143

Question 12

How do you model transverse waves using water ripples?

Answer 12

As the surface of the water moves up and down, you can see that the wave travels but the water doesn’t. If you put a rubber duck on the water then it won’t move away.

Question 13

How do you calculate wave velocity?

Answer 13

wave velocity (m/s) = wavelength (m) x frequency (Hz)

Question 14

How do you model longitudinal waves using sound?

Answer 14

As you speak, the wave moves away from your mouth but the air doesn’t.

Question 15

How do you measure the velocity of ripples?

Answer 15

You can use a ripple tank, and to find the wavelength you can use a flashing ‘strobe’ to freeze the waves so you can measure their length. You can then calculate the frequency by counting the number of rotations of the motor in 10s and dividing this by 10. You then use the equation to calculate velocity.

Question 16

How do you measure the velocity of sound (2)?

Answer 16

You can time how long it takes to hear an echo of a clap when you are a distance from the wall, and use the equation linking distance, velocity and time.
You can connect a pair of microphones over a certain distance apart to an oscilloscope, which will sow the variation of pressure with time.

Question 17

What are electromagnetic waves?

Answer 17

EM waves are transverse waves that are transmitted through space, and they all have the same velocity.

Question 18

How is energy transferred in EM waves?

e.g.

Answer 18

EM waves transfer energy from source to absorber. E.g. sources such as the Sun have electromagnetic waves tat are absorbed by the skin.

Question 19

What is the order of the main groupings of the electromagnetic spectrum?

Answer 19

Radio waves, microwaves, infra-red, visible light, ultraviolet, x-rays, gamma rays
This is in the order of long to short wavelength (10^2 - 10^-16)
This is in the order of low to high frequency

Question 20

What can our eyes see?

Answer 20

Our eyes can only detect a limited range of frequencies of the electromagnetic spectrum, which is visible light

Question 21

How do you produce a radio wave?

Answer 21

Radio waves can be produced by, or can themselves induce, oscillations in electrical circuits

Question 22

What is light?

Answer 22

Light is an electromagnetic wave

Question 23

Give examples of some practical uses of electromagnetic waves in the radio region

Answer 23

TV and radio stations transmit television and radio signals by adding sound and picture information to radio waves

Question 24

Give examples of some practical uses of electromagnetic waves in the microwave region (3)

Answer 24

Your phone communicates with transmitters using microwaves. They are also used to communicate with satellites, and for wifi and bluetooth systems
Microwaves are also used in a microwave oven, where the water and fat absorb the microwaves, heating up the food

Question 25

Give examples of some practical uses of electromagnetic waves in the infra-red region (4)

Answer 25

Infra-red radiation cooks food in a grill or oven.
Infrared from a radiator can heat you by transferring energy to a thermal store
Remote controls use pulses of infrared to communicate with televisions
You can also send information at high speeds using infrared pulses down optic fibres

Question 26

Give examples of some practical uses of electromagnetic waves in the visible light region (2)

Answer 26

Ships sometimes communicate using visible light and Morse Code
Lasers in CDs, DVDs and Blu-ray Discs use visible light

Question 27

Give examples of some practical uses of electromagnetic waves in the ultraviolet region (4)

Answer 27

Helps to produce vitamin D, which you need for strong bones
Bodily fluids glow in ultraviolet light
You can use ultraviolet to detect forged bank notes
Kills bacteria in water

Question 28

Give examples of some practical uses of electromagnetic waves in the X-ray region (1)

Answer 28

X-rays can kill skin cancer or other cancer cells

Question 29

Give examples of some practical uses of electromagnetic waves in the Gamma ray region

Answer 29

Gamma rays can kill cancer cells, and also bacteria on food

Question 30

Describe how ultra-violet waves can have hazardous effects, notably on human bodily tissues (2)

Answer 30

Ultraviolet can damage the DNA in the cells in your skin. The cells can grow rapidly and cause skin cancer
If you expose your eyes to ultraviolet you can develop cataracts which makes your corneas cloudy

Question 31

Describe how X-rays can have hazardous effects, notably on human bodily tissues

Answer 31

X-rays can damage the cells and cause cancer

Question 32

Describe how gamma rays can have hazardous effects, notably on human bodily tissues

Answer 32

Gamma rays can damage and kill the cells in the body

Question 33

What can different substances do?

Answer 33

Different substances may absorb, transmit, refract or reflect electromagnetic waves in ways that vary with wavelength.