Wave Behaviour (OCR Gateway GCSE Physics)

Look at the diagram of a water wave.

Answer = .........................cm [1]

Answer = .........................cm [1]

Answer = .........................m/s [2]

Water waves are transverse and sound waves are longitudinal.

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Look at the diagram of the electromagnetic spectrum.

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Some students try to measure the speed of sound, as shown in Fig. 24.1.

One student makes a loud sound by clapping her hands.

The sound of the clap reflects from the gym wall causing an echo.

Another student measures the time between hearing the clap and hearing the echo.

Fig. 24.1

They repeat the experiment three times and record their results in the table below.

Calculate the mean time taken for the sound of the clap to return, using suitable values from the table.

Mean time taken = ................................ s [1]

Use your answer to (a)(i) and the equation: distance travelled = speed × time

Give your answer to 3 significant figures.

Speed of sound = ................................ m/s [4]

1 .......................................................................................

2 .......................................................................................

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Ultrasound wave pulses are used by vets to scan inner tissues inside animals.

The ultrasound pulses partially reflect from different layers of tissue. These reflected wave pulses (echoes) are collected by the detector as shown in Fig. 24.2.

Fig. 24.2

In a scan using ultrasound pulses, three layers of tissue are detected, with each layer having a different thickness.

Describe and explain how the results from the detector can show:
•   that there are three layers
•   that each layer has a different thickness.

A teacher uses water waves in a ripple tank to demonstrate transverse waves.

She makes measurements of the water waves.

The frequency of the water waves is 0.5Hz.

Answer = ......................... [1]

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A student watches a ball game on the school field.

The student sees the ball being hit with a bat but he hears the sound a short time after. This is because the speed of light is much greater than the speed of sound.

Describe an experiment which measures the speed of sound in air.

In your answer describe the measurements, calculations and procedures needed to gather accurate and reliable results.

You may draw a diagram as part of your answer.

Higher Only

Look at the diagram of a human ear.
Sound wave disturbances, outside the ear, transfer energy to the small hairs (cilia) inside the cochlea.

The cochlea then sends nerve impulses along the auditory nerve to the brain.

Explain how sound wave disturbances in the air outside the ear transfer to the small hairs (cilia) inside the cochlea.

A crowd makes a Mexican wave.

A Mexican wave starts with people lifting and lowering their arms.
The Mexican wave continues by people, next to them, lifting and lowering their arms.

Why is a Mexican wave an example of a transverse wave?

In the classroom a teacher demonstrates waves using a rope.

Look at the diagram of the wave.

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Answer = ......................... seconds [3]

Higher Only

Ultrasound scans are used to produce images of tissues inside the body.

Ultrasound waves are emitted.

The waves reflect from layers of tissue inside the body.

Explain how the reflections are used to produce an image of the tissues.

Ultrasound and X-rays are used to scan patients in hospitals.

Complete the table to show a medical use, benefits and risk of using these waves to scan patients.

Fig. 20.1 is a graph of a wave.

Fig. 20.1

Amplitude = ................................ cm [1]

What is meant by the term frequency?

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A water wave has a frequency of 0.25 Hz and a wavelength of 6.0 m.

Calculate the speed of the wave.

Speed of the wave = ................................ m/ s [3]

Surface water waves can be modelled using a slinky spring.

A student holds one end of the spring on a table. The other end is fixed to a wall.

Fig. 20.2 shows the spring viewed from above the table.

Fig. 20.2

Describe what happens to the transverse wave at the wall.

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         This is what the coils in the spring look like after a short time:

Fig. 20.3

This model of a water wave shows that the wave travels not the water.

Explain why.

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