Saturday, June 24, 2017

What, to two significant figures, are the period, the frequency and the amplitude of the wave represented by the graph?






Question 1
What, to two significant figures, are the period, the frequency and the amplitude of the wave represented by the graph?


period / s        frequency / Hz           amplitude / m
A          0.0027             370                              0.0067
B          0.0031             320                              0.013
C         0.0035             290                              0.0067
D         0.0042             240                              0.013





Reference: Past Exam Paper – June 2014 Paper 12 Q22





Solution:
Answer: C.
A graph of displacement against time is given. The y-axis gives displacement in ‘m’ and the x-axis gives time in ‘ms’.

Period can be directly obtained from the time axis.
3.5 waves correspond to 12.1 ms.
3.5 T = 12.1×10-3 s
Period T = 12.1×10-3 / 3.5 = 0.0035 s

Frequency = 1 / T = 1 / 0.0035 = 290 Hz

Amplitude is the maximum displacement. This can be obtained from the y-axis.
Amplitude = 6.7 mm = 0.0067 m

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