P-waves and S-waves are two types of seismic wave caused by earthquakes - AQA - GCSE Physics - Question 3 - 2018 - Paper 1
Question 3
P-waves and S-waves are two types of seismic wave caused by earthquakes.
Which one of the statements about P-waves and S-waves is correct?
Tick one box.
P-waves an... show full transcript
Worked Solution & Example Answer:P-waves and S-waves are two types of seismic wave caused by earthquakes - AQA - GCSE Physics - Question 3 - 2018 - Paper 1
Step 1
Which one of the statements about P-waves and S-waves is correct?
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Answer
P-waves are longitudinal and S-waves are transverse. P-waves, being primary waves, move in a compressional manner, while S-waves, being secondary waves, move in a shear manner.
Step 2
Calculate the frequency of the P-wave shown in Figure 3.
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Answer
The frequency of the P-wave can be calculated using the formula provided in the next part of the question. Assuming the figure shows a period of 0.4 seconds, the frequency is calculated as:
f = rac{1}{T} = rac{1}{0.4} = 2.5 ext{ Hz}
Step 3
Write down the equation which links frequency, wavelength and wave speed.
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Answer
The relationship between frequency (f), wavelength (λ), and wave speed (v) is given by the equation:
v=fimesextλ
Step 4
Calculate the wavelength of the P-wave.
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Answer
Using the wave speed from the question, we have:
Given, the speed of the P-wave, v=7200extm/s and from previous calculation, f=2.5extHz.
Why does the movement of the bar magnet induce a potential difference across the coil?
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Answer
The movement of the bar magnet changes the magnetic field around the coil. According to Faraday's law of electromagnetic induction, this change in magnetic field induces an electromotive force (EMF) or potential difference across the coil.
Step 6
Why is the induced potential difference across the coil alternating?
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Answer
The induced potential difference is alternating because the direction of the magnet's motion changes. When the magnet moves towards the coil, the induced potential difference is in one direction, and when it moves away, the induced potential difference reverses, creating an alternating wave.
Step 7
Which statement describes the movement of the magnet when the induced potential difference is zero?
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Answer
The magnet is stationary. When there is no change in the magnetic field (i.e., when the magnet is at rest), the induced potential difference across the coil will be zero.
Step 8
Suggest two changes to the design of the seismometer that would make it more sensitive to small vibrations.
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Answer
Use a stronger magnet for greater induction of potential difference.
Increase the number of turns in the coil to enhance the electromagnetic induction effect, making the device more responsive to small vibrations.
