7.1. Progressive waves
A subsection of Physics, 9702, through 7. Waves
Listing 10 of 202 questions
A sound wave is detected by a microphone that is connected to a cathode-ray oscilloscope (CRO). The trace on the screen of the CRO is shown in . 1.0 cm 1.0 cm The time-base setting of the CRO is 2.0 × 10–5 s cm–1. Determine the frequency of the sound wave. frequency = Hz The intensity of the sound wave is now doubled. The frequency is unchanged. Assume that the amplitude of the trace is proportional to the amplitude of the sound wave. On , sketch the new trace shown on the screen. The time-base is now switched off. Describe the trace seen on the screen. A beam of light of a single wavelength is incident normally on a diffraction grating, as illustrated in . 16° 16° diffraction grating light beam second order second order zero order (not to scale) does not show all of the emerging beams from the grating. The angle between the second-order emerging beam and the central zero-order beam is 16°. The grating has a line spacing of 3.4 × 10–6 m. Calculate the wavelength of the light. wavelength = m Determine the highest order of emerging beam from the grating. highest order =
9702_w20_qp_23
THEORY
2020
Paper 2, Variant 3
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A progressive wave travels through a medium. The wave causes a particle of the medium to vibrate along a line P. The energy of the wave propagates along a line Q. Compare the directions of lines P and Q if the wave is: a transverse wave a longitudinal wave. A tube is closed at one end. A loudspeaker is placed near the other end of the tube, as shown in . A A tube loudspeaker L (not to scale) The loudspeaker emits sound of frequency 1.7 kHz. The speed of sound in the air in the tube is 340 m s–1. A stationary wave is formed with an antinode A at the open end of the tube. There is only one other antinode A inside the tube, as shown in . Determine: the wavelength of the sound wavelength = m the length L of the tube L = m the maximum wavelength of the sound from the loudspeaker that can produce a stationary wave in the tube. maximum wavelength = m Two polarising filters are arranged so that their planes are vertical and parallel. The first filter has its transmission axis at an angle of 35° to the vertical and the second filter has its transmission axis at angle α to the vertical, as shown in . 35° α incident light beam, intensity 8.5 W m–2 intensity 5.2 W m–2 first filter second filter transmission axis of filter Angle α is greater than 35° and less than 90°. A beam of vertically polarised light of intensity 8.5 W m–2 is incident normally on the first filter. Show that the intensity of the light transmitted by the first filter is 5.7 W m–2. The intensity of the light transmitted by the second filter is 5.2 W m–2. Calculate angle α. α = °
9702_s23_qp_22
THEORY
2023
Paper 2, Variant 2
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Questions Discovered
202