3.4. Sound
A subsection of Physics, 5054, through 3. Waves
Listing 10 of 120 questions
An oscilloscope is a device used to display waveforms. Inside the oscilloscope, a beam of electrons is emitted from a metal filament by thermionic emission. The emitted electrons are accelerated away from the filament by a potential difference of 2000 V. State what must happen to the metal filament for thermionic emission to occur. Explain why the electrons accelerate away from the filament. The charge on one electron is 1.6 × 10−19 C. Calculate the maximum kinetic energy of one electron after it has been accelerated through 2000 V. kinetic energy = is the trace on the screen of the oscilloscope. 1 division 1 division The settings on the oscilloscope are 10 ms / division for the x-axis and 3.0 V / division for the y-axis. Calculate the amplitude of the trace shown in . amplitude = Calculate the time for one oscillation (complete wavelength) of the trace shown in . time = The trace shown in is caused by a sound. The sound travels through the air to a microphone from the place that it is made. The microphone is connected to the oscilloscope which displays the waveform shown. Sound is a type of wave. State which type. Describe the motion of the air molecules as the sound passes through the air to the microphone. Describe and explain how the trace on the screen changes as the pitch of the sound becomes higher. The settings on the oscilloscope are unchanged. A student investigates what happens when a diode is connected between the microphone and the oscilloscope. shows the circuit that he uses. diode oscilloscope output from microphone Without the diode, the output from the microphone is an alternating current and the trace is as shown in on page 18. Describe the action of the diode on the current from the microphone. On the grid in , sketch the trace seen on the screen when the diode is used.
5054_s20_qp_22
THEORY
2020
Paper 2, Variant 2
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This question is about the sound produced by a mobile phone and the energy changes while it is operating. The sound produced by a ringing phone consists of two notes, one after the other. shows the trace on an oscilloscope screen produced by the first of the notes. The second note is louder and has a higher pitch. On , continue the trace to show what happens when the second note is sounding. Explain the differences between the two traces. The mobile phone contains a rechargeable battery. Energy is stored inside the battery as it is charged. Describe the useful energy change that takes place inside the battery as it is charged from the mains. Use
5054_w05_qp_2
THEORY
2005
Paper 2, Variant 0
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shows one swimmer in a race starting before the signal. loudspeakers The swimmer is called back by a loud, low-pitched sound from a loudspeaker positioned just at water level. The speed of sound in air is 330 m / s. Describe how the loudspeaker causes sound to travel through the air. Explain, in terms of wave properties, what is meant by loud and low-pitched. The swimmer is 0.57 m from the loudspeaker when he hears the sound. Calculate the time taken for the sound to reach him through the air. Explain how the time taken differs when sound travels the same distance through air and through water. The loudspeaker produces sound of frequency 0.20 kHz. Calculate the wavelength of this sound. Draw a diagram to show what is meant by the term wavelength when applied to a longitudinal wave such as sound.
5054_w08_qp_2
THEORY
2008
Paper 2, Variant 0
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shows a girl standing a few hundred metres in front of a large building. (not to scale) The girl uses a signal generator and a loudspeaker to send a short pulse of sound towards the building. The sound has a frequency of 3700 Hz. A short time later, the girl hears an echo. State what is meant by the term echo. The pitch of the echo is the same as that of the original sound but the echo is not as loud. State what has happened to the amplitude of the sound wave, the frequency of the sound wave. The speed of sound in air is 330 m / s. Calculate the wavelength of this sound. wavelength =
5054_w17_qp_22
THEORY
2017
Paper 2, Variant 2
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Questions Discovered
120