The diagram shows an oscilloscope screen displaying two signals. Signal X has a frequency of 50 Hz and peak voltage of 12 V.

Question 4

The diagram shows an oscilloscope screen displaying two signals.

Signal X has a frequency of 50 Hz and peak voltage of 12 V.

What is the period and peak voltage of signal Y?

period / ms                  peak voltage / V

A                      20                                4

B                      20                                12

C                     50                                4

D                     50                                12

Reference: Past Exam Paper – November 2009 Paper 12 Q3

Solution:

Answer: A.

Vertically, the screen represents the peak voltage (starting from the central horizontal line) and horizontally, it represents the time.

Consider signal X.

3 squares represent 12V

1 square represents (12 / 3 =) 4 V

Frequency = 1 / T = 50 Hz

Period T = 1 / 50 = 0.02 s = 20 ms

Signal Y has the same period as signal X since one complete cycle occupies the same space.

Period of signal Y = 20 ms

The peak voltage of signal Y is represented by 1 square = 1 × 4V = 4 V