8.1. Stationary waves
A subsection of Physics, 9702, through 8. Superposition
Listing 10 of 102 questions
By reference to the direction of propagation of energy, state what is meant by a transverse wave. State the principle of superposition. Circular water waves may be produced by vibrating dippers at points P and Q, as illustrated in . Q R wavefront P 44 cm 29 cm (not to scale) The waves from P alone have the same amplitude at point R as the waves from Q alone. Distance PR is 44 cm and distance QR is 29 cm. The dippers vibrate in phase with a period of 1.5 s to produce waves of speed 4.0 cm s−1. Determine the wavelength of the waves. wavelength = cm By reference to the distances PR and QR, explain why the water particles are at rest at point R. A wave is produced on the surface of a different liquid. At one particular time, the variation of the vertical displacement y with distance x along the surface of the liquid is shown in . 0 0 1.0 –1.0 –0.5 0.5 y / cm x / cm The wave has intensity I1 at distance x = 2.0 cm and intensity I2 at x = 10.0 cm. Determine the ratio intensity I2 intensity I1 . ratio = State the phase difference, with its unit, between the oscillations of the liquid particles at distances x = 3.0 cm and x = 4.0 cm. phase difference =
9702_m16_qp_22
THEORY
2016
Paper 2, Variant 2
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A tube of length L is open at both ends. A stationary wave is set up in this tube when a tuning fork vibrating with frequency fx is held at one end. This is the lowest frequency of stationary wave that can be formed in this tube. Another tube of length 2L is closed at one end. A stationary wave is set up in this tube when a tuning fork vibrating with frequency fy is held at the open end. This is the lowest frequency of stationary wave that can be formed in this tube. L frequency fx 2L frequency fy Assume the end correction for each tube is negligible. Which equation is correct?
9702_m18_qp_12
MCQ
2018
Paper 1, Variant 2
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State the principle of superposition. A transmitter produces microwaves that travel in air towards a metal plate, as shown in . X microwave transmitter microwave receiver metal plate The microwaves have a wavelength of 0.040 m. A stationary wave is formed between the transmitter and the plate. Explain the function of the metal plate. Calculate the frequency, in GHz, of the microwaves. frequency = GHz A microwave receiver is initially placed at position X where it detects an intensity minimum. The receiver is then slowly moved away from X directly towards the plate. 1. Determine the shortest distance from X of the receiver when it detects another intensity minimum. distance = m 2. Determine the number of intensity maxima that are detected by the receiver as it moves from X to a position that is 9.1 cm away from X. number =
9702_m21_qp_22
THEORY
2021
Paper 2, Variant 2
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State the conditions required for the formation of a stationary wave. State the phase difference between any two vibrating particles in a stationary wave between two adjacent nodes. phase difference = ° A motorcycle is travelling at 13.0 m s–1 along a straight road. The rider of the motorcycle sees a pedestrian standing in the road directly ahead and operates a horn to emit a warning sound. The pedestrian hears the warning sound from the horn at a frequency of 543 Hz. The speed of the sound in the air is 334 m s–1. Calculate the frequency, to three significant figures, of the sound emitted by the horn. frequency = Hz The motorcycle rider passes the stationary pedestrian and then moves directly away from her. As the rider moves away, he operates the horn for a second time. The pedestrian now hears sound that is increasing in frequency. State the variation, if any, in the speed of the motorcycle when the rider operates the horn for the second time. A beam of vertically polarised monochromatic light is incident normally on a polarising filter, as shown in . 20° vertically polarised incident light beam, intensity I0 transmitted light beam, intensity IT transmission axis of filter polarising filter The filter is positioned with its transmission axis at an angle of 20° to the vertical. The incident light has intensity I0 and the transmitted light has intensity IT. By considering the ratio IT I0 , calculate the ratio amplitude of transmitted light amplitude of incident light . Show your working. ratio = The filter is now rotated, about the direction of the light beam, from its starting position shown in . The direction of rotation is such that the angle of the transmission axis to the vertical initially increases. Calculate the minimum angle through which the filter must be rotated so that the intensity of the transmitted light returns to the value that it had when the filter was at its starting position. angle = °
9702_m22_qp_22
THEORY
2022
Paper 2, Variant 2
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Questions Discovered
102