GCSEScienceWJECScience (Double Award)PhysicsExam QuestionsElectricity, Energy & WavesFeatures of Waves

Features of Waves (WJEC GCSE Science (Double Award): Physics): Exam Questions

Exam code: 3430

2 hours18 questions

2 marks

The diagram shows the 7 regions of the electromagnetic (em) spectrum in order.

Diagram of the electromagnetic spectrum: gamma rays, A, B, visible light, infra-red, microwaves, radio waves, with an arrow showing increasing wavelength

Use only the words given in the box below to answer the following questions.

cosmic rays

X-rays

ultrasound

water

ultraviolet

(i) Name the region labelled A. ..................................

[1]

(ii) Name the region labelled B. .................................

[1]

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4 marks

Use the electromagnetic spectrum diagram from part (a) to answer part (b).

(i) Complete the following sentence by underlining the correct word in the bracket.

[1]

The arrow shown on the electromagnetic spectrum above represents increasing (amplitude / wavelength / frequency).

(ii) Waves in the electromagnetic spectrum all travel at the same speed in a vacuum.

Tick (✓) the three correct statements that describe other properties of em waves.

[3]

$box enclose space space space space space space end enclose$ All transverse.

$box enclose space space space space space space end enclose$ All ionising.

$box enclose space space space space space space end enclose$ All transfer energy.

$box enclose space space space space space space end enclose$ All longitudinal.

$box enclose space space space space space space end enclose$ All travel through space.

$box enclose space space space space space space end enclose$ All given out by radioactive materials.

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8 marks

A teacher demonstrates waves using a ripple tank.

She changes the frequency of the waves produced and the class observes the effect on their wavelength.

Laboratory setup with a movable lamp and solar cell on a sloping surface, connected by wires to a meter, showing investigation of light intensity on output

Next, the class investigates the link between frequency and wavelength using a virtual ripple tank simulation.

The table below shows their results.

Frequency (Hz)	$\frac{1}{frequency}$ (s)	Wavelength (cm)
20.0	0.05	1.0
10.0	0.10	2.0
6.7	0.15	3.0
5.0	0.20	4.0
4.0	0.25	5.0

(i) Plot the data on the grid below and draw a suitable straight line.

[3]

Blank graph with gridlines, x-axis labelled 1/frequency in seconds from 0.00 to 0.25, y-axis labelled wavelength in centimetres from 0.0 to 5.0

(ii) Complete the following sentences by underlining the correct word or phrase in the brackets.

[2]

I. As $\frac{1}{frequency}$ increases the wavelength [increases / decreases / stays the same].

II. As frequency increases the wavelength [increases / decreases / stays the same].

(iii)

I. Use data from the table to state the wavelength of the waves at a frequency of 10 Hz.

[1]

Wavelength = .......... cm

II. Use the equation:

wave speed = frequency × wavelength

to determine the speed of the waves at a frequency of 10 Hz.

[2]

Speed = .......... cm/s

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9 marks

(i) Electromagnetic waves are used to communicate with satellites. Some satellites remain above the same point on the Earth to allow constant communication.

Complete the following sentences about communications satellites by underlining the correct word or phrase in the brackets.

[4]

Electromagnetic waves are (longitudinal / parallel / transverse) waves.

TV signals are sent to satellites in (geothermal / geosynchronous / geostationary) orbits using (microwaves / visible light / gamma rays).

These satellites orbit above the (poles / equator / axis) of the Earth.

(ii) A satellite orbits the Earth in a circular orbit, once every 24 hours. The radius of its orbit is 42 164 km.

I. Use the equation:

circumference of a circle = $2 π r$ (where $r$ = radius and $π$ = 3.14)

to calculate the distance the satellite travels in one orbit.

[1]

Distance = .......... km

II. Use the equation:

speed = $\frac{distance}{time}$

to calculate the speed of the satellite in km/h.

[2]

Speed = .......... km/h

(iii) Maddie suggests that the satellite orbits at the same speed as a point on the Earth's surface moves, so that it always stays above the same point on the Earth.

Explain whether or not you agree.

[2]

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More Revision Notes you might like

Region	Wavelength (m)	Frequency (Hz)
radio	> 1 $\times$ 10^-1	..........
microwave	1 $\times$ 10^-3 to 1 $\times$ 10^-1	3 $\times$ 10⁹to 3 $\times$ 10¹¹
infra-red	..........	3 $\times$ 10¹¹ to 4 $\times$ 10¹⁴
visible	..........	4 $\times$ 10¹⁴ to 7.5 $\times$ 10¹⁴
ultraviolet	1 $\times$ 10^-8 to 4 $\times$ 10^-7	7.5 $\times$ 10¹⁴to 3 $\times$ 10¹⁶
X-ray	1 $\times$ 10^-11 to 1 $\times$ 10^-8	3 $\times$ 10¹⁶ to 3 $\times$ 10¹⁹
gamma ray	< 1 $\times$ 10^-11	..........

Satellite	Height above Earth (km)	Period (hours)
1	21 450	12.9
2	24 000	15
3	36 000	24
4	507	1.6
5	1 090	1.8
6	20 200	12

Depth of water, d (m)	$\sqrt{d}$	Wave speed, v (m/s)
0	0	0
0.5	0.71	2.21
1.0	1.00	3.13
1.5	..........	3.83
2.5	1.58	4.95
3.0	1.73	5.42
3.5	1.87	..........
4.0	2.00	6.26

Region	Radio waves	Microwaves	Infra-red	Visible
Wavelength (m)	.....................	.....................	.....................	.....................

Speed of signal to satellite	3 × 10⁸m/s
Speed of signal in cable	2 × 10⁸m/s
Distance from A to B through the cable	6 × 10⁶ m
Distance from A to B via the satellite	7.2 × 10⁷ m

Region	Energy (J) in incorrect order	Energy (J) in correct order
radio	> 2 $\times$ 10^-14	..........
microwave	3 $\times$ 10^-19 to 5 $\times$ 10^-19	..........
visible	2 $\times$ 10^-17 to 2 $\times$ 10⁻¹⁴	..........
X-ray	2 $\times$ 10^-24 to 2 $\times$ 10^-22	..........
gamma ray	< 2 $\times$ 10^-24	..........

Depth of water (cm)	Time (s)			Mean time (s)	Mean wave speed (cm/s)
Depth of water (cm)	Trial 1	Trial 2	Trial 3	Mean time (s)	Mean wave speed (cm/s)
0.5	4.57	4.58	4.52	4.56	21.9
1.0	3.22	3.24	2.61	3.02	33.1
1.5	2.61	2.62	2.64	2.62	38.1
2.0	2.29	2.28	2.24	2.27	44.1
2.5	2.01	2.02	1.98	2.00	50.0