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Which control on the oscilloscope should be used to centre the trace vertically on the screen? Tick (v) one box - AQA - A-Level Physics - Question 1 - 2022 - Paper 3
Question 1
Which control on the oscilloscope should be used to centre the trace vertically on the screen? Tick (v) one box. X-shift Y-gain Y-shift When the hammer hits end L,... show full transcript
Worked Solution & Example Answer:Which control on the oscilloscope should be used to centre the trace vertically on the screen? Tick (v) one box - AQA - A-Level Physics - Question 1 - 2022 - Paper 3
Step 1
Step 2
Deduce the speed of sound in the steel rod.
Answer
To find the speed of sound, we can use the formula:
v = \frac{d}{t}$$ where: - $d$ is the distance between L and R, which is 0.870 m - $t$ is the time measured on the oscilloscope. Given that the signal displays 6.0 divisions with a time base of 50 ms/div, the total time is: $$t = 6.0\, \text{divisions} \times 50\, \text{ms/div} = 300\, \text{ms} = 0.300\, \text{s}$$ Now substituting the values: $$v = \frac{0.870\, \text{m}}{0.300\, \text{s}} = 2.90\, \text{m s}^{-1}$$Step 3
Explain how using the longer rod affects the waveform displayed.
Answer
Using a steel rod of twice the length means that the sound wave will have to travel a greater distance. This results in a longer time interval before the wave returns to the point of origin, potentially showing an extended echo on the oscilloscope. Specifically, the number of cycles displayed would be fewer since the wavelength extends further due to increased length. The time between echoes would also be greater, requiring adjustments to the time base for clarity.
Step 4
Explain any changes needed to get an accurate result for the speed.
Answer
To accurately measure the speed using the longer rod, the oscilloscope's time base setting would need to be adjusted to accommodate the longer travel time. This could involve doubling the time/div setting on the oscilloscope, which would allow all the cycles to be displayed clearly. An accurate measurement of the time taken for the waves to travel and reflect would be essential for calculating the speed correctly.