The diagram shows the waveform of a signal displayed on a cathode-ray oscilloscope.

Question 15

The diagram shows the waveform of a signal displayed on a cathode-ray oscilloscope.

The time-base is set at 5.0 ms per division.

The Y-gain is set at 5.0 mV per division.

What are the amplitude and the frequency of the signal?

amplitude / mV            frequency / Hz

A                     10                                50

B                     10                                100

C                     20                                50

D                     20                                100

Reference: Past Exam Paper – November 2018 Paper 11 Q23

Solution:

Answer: A.

The amplitude is measured (vertically) starting from the central line to the peak.

Y-gain = 5.0 mV per div

Amplitude = 2 div = 2 × 5.0 = 10 mV

The period is measured horizontally. One complete wave occupies 4 div.

Time-base setting = 5.0 ms per div

Period T = 4 div = 4 × 5.0 = 20 ms = 20×10^-3 s

 

Frequency = 1 / T = 1 / (20×10^-3) = 50 Hz