Complete Electronics Self-Teaching Guide with Projects

Phase Shift of an RC Circuit

20 In both of the circuits shown in Figure 6.26, the output voltage is different from the input voltage.

Figure 6.26

Question

In what ways do they differ? _____

Answer

The signal is attenuated, or reduced. The amount of attenuation depends upon the frequency of the signal. Circuit 1 will pass high-frequency signals while blocking low-frequency signals. Circuit 2 will pass low-frequency signals while blocking high-frequency signals.

21 The voltage is also changed in another way. The voltage across a capacitor rises and falls at the same frequency as the input signal, but it does not reach its peak at the same time, nor does it pass through zero at the same time. You can see this when you compare the V_out curves to the V_in curves in Figure 6.27.

Note The numbered graphs in Figure 6.27 are produced by the corresponding numbered circuits in Figure 6.26.

Figure 6.27

Questions

A. Examine graph (1). Is the output voltage peak displaced to the right or the left? _____

B. Examine graph (2). Is the output voltage peak displaced to the right or the left? _____

Answers

A. To the left

B. To the right

22 The output voltage waveform in graph (1) of Figure 6.27 is said to lead the input voltage waveform. The output waveform in graph (2) ...