7. Waves
A section of Physics, 9702
Listing 10 of 368 questions
Two progressive sound waves meet to form a stationary wave. The two waves have the same amplitude, wavelength, frequency and speed. State the other condition that must be fulfilled by the two waves in order for them to produce the stationary wave. A stationary wave is formed on a string that is stretched between two fixed points A and B. shows the string at time t = 0 when each point is at its maximum displacement. A B Distance AB is 0.80 m. The period of the stationary wave is 0.016 s. On , sketch a solid line to show the position of the string: ● at time t = 0.004 s (label this line P) ● at time t = 0.024 s (label this line Q). Determine the speed of a progressive wave along the string. speed = m s–1 A beam of vertically polarised light of intensity I0 is incident normally on a polarising filter that has its transmission axis at 30° to the vertical, as shown in . 30° intensity I0 intensity I1 intensity I2 vertically polarised incident light beam, transmitted beam, transmitted beam, polarising filter with transmission axis at 30° to the vertical second polarising filter with transmission axis at 90° to the vertical The transmitted light from the first polarising filter has intensity I1. This light is then incident normally on a second polarising filter that has its transmission axis at 90° to the vertical. The transmitted light from the second filter has intensity I2. Calculate: the ratio I1 I0 I1 I0 = the ratio I2 I0 . I2 I0 =
9702_w22_qp_22
THEORY
2022
Paper 2, Variant 2
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A train travels at constant speed along a straight horizontal track towards an observer standing adjacent to the track, as shown in . train track observer The train sounds its horn continuously as it approaches the observer. The horn emits a sound of constant frequency 251 Hz. The frequency of sound heard by the observer is 291 Hz. The speed of sound in air is 340 m s–1. Calculate the speed of the train. speed = m s–1 The train approaches and then passes the observer. The intensity I of the sound heard by the observer varies with the distance d of the horn from the observer. When the horn is at a distance x0 from the observer, the intensity I of the sound heard is I0 and the amplitude A of the sound wave at the observer is A0. shows the variation with d / x0 of I / I0 as the train moves away from the observer. d / x0 0.2 0.4 0.6 0.8 1.0 I / I0 d / x0 0.2 0.4 0.6 0.8 1.0 A / A0 State the relationship between amplitude A and intensity I for a progressive wave. On , sketch the variation with d / x0 of A / A0.
9702_w23_qp_23
THEORY
2023
Paper 2, Variant 3
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Questions Discovered
368