Properties of Waves (Edexcel GCSE Physics)

Figure 11 shows a large tank of water.

Figure 11

The tank of water is used to study water waves.

i) Water waves are transverse waves.

Give another example of a transverse wave.

[1]

ii) Figure 12 shows a side view of part of the tank.

Figure 12

A water wave is moving from L to M.

Calculate the wavelength of the wave.

wavelength = ...................................................... m[2]

iii) A technician stands at the side of the tank.

He counts the peaks of the waves as they pass him.

12 peaks pass the technician in a time of 15 s.

Calculate the frequency of the wave.

frequency = .................................................. Hz[2]

Figure 13 shows part of the inside of the Earth below the surface.

Figure 13

An earthquake starts at Q. A seismic wave travels from Q to S. The seismic wave is a longitudinal wave.

i) Draw arrows on Figure 13 to show how the rock at R moves when the seismic wave passes through R.

[2]

ii) The frequency of the seismic wave is 12 Hz.

The wave speed of the seismic wave is 7 km/s.

Calculate the wavelength of the seismic wave, in metres. Use the equation

wavelength = .................................................... m[3]

A technician measured the frequency of the water wave in part (a) by counting how many waves passed him in 15 s.

Explain why this would not be a suitable method for measuring the frequency of the seismic wave in part (b)(ii).

A sound wave in air travels a distance of 220m in a time of 0.70s.

i) State the equation linking speed, distance and time.

[1]

ii) Calculate the speed of the sound wave in air.

wave speed = ..................................................... m/s[2]

Figure 2 shows water waves spreading out from a source.

A student measures the wavelength of the waves. He uses a ruler to measure the distance from one crest to the next crest.

Figure 2

Explain how to improve the student's method for measuring the wavelength.

Sound waves are longitudinal waves.

Water waves are transverse waves.

Describe the difference between longitudinal waves and transverse waves.

Which colour of visible light has the longest wavelength?

Some television remote controls use infrared radiation and other remote controls use radio waves.

Explain why an infrared remote control may not switch on the television from behind an armchair but a radio wave remote control always will.

Figure 2 is a diagram of a water wave.

A cork is floating on the water.

Figure 2

i) Use the scale on the diagram to measure the wavelength of the wave.

wavelength = ...................................................... cm[2]

ii) Describe the motion of the cork.

You should include how the cork moves relative to the direction of travel of the wave.

[2]

A different water wave has a wavelength of 0.25 m and a frequency of 1.5 Hz.

Calculate the wave speed.

 wave speed = .............................................. m/s

A radio station transmits on 97.4 MHz. To receive the waves an aerial needs a length equal to half the wavelength of the radio waves being transmitted.

Calculate the length of the aerial needed.

The speed of the radio waves is 3.00 × 10⁸ m/s.

length of aerial = .............................................................. m

To investigate refraction in a rectangular glass block a student uses the apparatus shown in Figure 5.

Figure 5

Describe how the student should measure the angle of refraction.

Higher Tier Only

Figure 6 is a simplified diagram to show radio waves from a transmitter moving upwards, then meeting a boundary between lower and upper layers of the atmosphere.

Figure 6

Explain what happens to the radio waves after they meet the boundary between the lower and upper layers as shown in Figure 6.

Your explanation should refer to changes in direction and speed of the waves.

Four students and their teacher do an experiment to measure the speed of sound in air.

The teacher stands at a distance and fires a starting pistol into the air.

The students see the flash when the pistol is fired.

They measure the time from when they see the flash to when they hear the bang.

A student drew a diagram of the arrangement as shown in Figure 7.

Figure 7

The students obtained a value of 240 m/s for the speed of sound.

The accepted value, in a science data book, is 343 m/s.

i) Calculate the difference between the students’ value and the accepted value as a percentage of the accepted value.

percentage difference = ............................................... %[2]

ii) When the distance was 100m, the students measured the following times:

Explain why their times vary so much.

[2]

iii) Explain one way the students might improve this experiment.

[2]

Figure 8 represents a sound wave coming from a loudspeaker and shows the effects on particles of the air at one instant in time.

Figure 8

i) Draw and label a distance of one wavelength in Figure 8.

[1]

ii) Describe the motion of the particles as the wave travels through the air.

[2]

Figure 1 shows part of a wave.

Figure 1

Use data from Figure 1 to calculate the wavelength of the wave.

wavelength = .............................................................. cm

i) Figure 2 shows a student sitting on the shore of a lake watching ripples on the surface of the water moving past a toy boat.

Figure 2

The student has a stopwatch.    

Describe how the student could determine the frequency of the ripples on the lake.

[3]

ii) The speed of a water wave is 1.5 m/s.

The frequency of the wave is 0.70 Hz.

Calculate the wavelength of this wave. Use the equation

v = f × λ

wavelength = ...................................... m[2]

iii) Water waves are transverse waves.

Describe the difference between transverse waves and longitudinal waves.

[2]

On a beach popular with surfers, one is watching a buoy move up and down with the waves, in Figure 1. 

Figure 1

She decides to plot a graph of how the height of the buoy varies with time - this is Figure 2.

Figure 2

Using a stopwatch, she measures the time from the buoy at its highest point to the peak of the 7th and smallest wave.

This takes 24.5 s.

Calculate the frequency of the waves.

Give your answer to 2 significant figures.

The surfer knows the distance to the buoy from the shore. 

Describe a method by which the surfer could determine the speed of the waves accurately.

The surfer determines that the wave speed is a value between 3.5 m/s and 4.5 m/s.

Calculate the possible range of wavelengths of the waves.

Give your answers to 2 significant figures.

Wavelength is between ........................ m and .................. m

Suggest why the surfer could only give a range of values for wave speed.

Higher Tier Only

Figure 1 shows an ultrasonic transmitter and receiver being used to detect cracks in steel rails. The transmitted and reflected pulses are shown on an oscilloscope's screen below.

The oscilloscope time base measures 10 microseconds per division on the horizontal axis.

Figure 1

Explain why there are two reflected pulses for transmitter B on the right.

Higher Tier Only

The speed of the ultrasound wave in steel is 6000 m/s.

Calculate the thickness of the steel in metres.

Higher Tier Only

Calculate the depth of the crack as a percentage of the thickness of the steel.