AQA AS Physics

Topic Questions

3.1 Longitudinal & Transverse Waves

1a4 marks

State what is meant by polarisation and explain how it is used to distinguish between transverse and longitudinal waves.

1b4 marks

An unpolarised light source passes horizontally through a fixed polarising filter A. An observer views the light emerging through a second polarising filter B, which may be rotated about point XY as shown in Figure 1.

Figure 1

3-1-s-q--q1b-medium-aqa-a-level-physics

The observer rotates B slowly through 360° clockwise. 

Relative to polarising filter A, at which angles of polarising filter B does the observer see the maxima and minima amount of daylight.

1c2 marks

On Figure 2 below, sketch how the light intensity reaching the observer varies as polarising filter B is rotated slowly through 360°.

Figure 2

3-1-s-q--q1c-medium-aqa-a-level-physics

1d2 marks

Explain why when the transmission axis of polarising filter B is perpendicular to the plane XY, the observer does not see horizontally polarised light. 

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2a2 marks

Figure 1 represents a progressive wave travelling from left to right on a stretched string.

Figure 1

3-1-s-q--q2a-medium-aqa-a-level-physics

The frequency of the wave is 30 Hz. Calculate the speed of the wave.

2b2 marks

State the phase difference between points X and Y on the string, giving an appropriate unit.

2c3 marks

Describe how the vertical displacement of point X on the string varies in the next period.

2d2 marks

Determine the phase difference between the current position of X and the position of X 0.0825 s later.

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3a3 marks

Explain briefly how transmission of energy by a longitudinal wave differs from transmission of energy by a transverse wave. Give one example of a transverse wave.

3b3 marks

With the aid of a clearly labelled diagram explain how a sound wave in air transmits energy away from its source.

3c3 marks

Short pulses of sound are reflected from a wall 30 m from the sound source. The reflected pulses return to the source after 0.18 s.

Calculate the speed of sound.

3d3 marks

Figure 1 represents the sound wave from part (c).

Figure 1

3-1-s-q--q3d-answer-medium-aqa-a-level-physics

Calculate the frequency of the sound wave.

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4a2 marks

Figure 1 shows two ways in which a wave can travel along a slinky spring.

Figure 1

3-1-s-q--q4a-medium-aqa-a-level-physics

Use arrows to draw the direction in which the points Q and R are about to move as each wave moves to the right.

4b3 marks

State which wave in part (a) electromagnetic waves are similar in nature to. 

Hence or otherwise, explain why it is important to correctly align a radio antenna in order to receive the strongest signal.             

4c2 marks

Light from a filament lamp is viewed through two polarising filters A and B shown in Figure 2.

Figure 2

3-1-s-q--q4c-medium-aqa-a-level-physics

Explain why the observer cannot see the light from the filament lamp.

4d3 marks

Explain how polaroid sunglasses can be used to view objects under the surface of water on a sunny day.

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5a2 marks

Explain the difference between compressions and rarefactions in a longitudinal wave.

5b3 marks

Musicians can use tuning forks to tune their instruments.

A tuning fork produces a specific frequency when it vibrates. 

Figure 1 shows a tuning fork vibrating in air at a single instant in time. The circles represent the positions of air particles in the sound wave.

Figure 1

3-1-s-q--q5b-medium-aqa-a-level-physics

The tuning fork is used to tune an orchestra at 0.44 kHz. 

Air particles vibrate in different phases in the direction in which the wave is travelling. 

Calculate the minimum separation of particles that vibrate 90° out of phase. 

            Speed of sound in air = 340 m s–1.     

5c2 marks

Figure 2 shows a snapshot of a progressive wave travelling from left to right on a violin string stretched between points X and Y. The violin is tuned to the same frequency as the tuning fork.

Figure 2

3-1-s-q--q5c-medium-aqa-a-level-physics

State the phase relationship between points A and B on the string. Label two more points, P and Q on Figure 2 which are  radians out of phase.

5d2 marks

Points X and Y in Figure 2 are 0.84 m apart. 

Calculate the speed of the wave travelling along the string.

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