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