Measurements of voltage

Consider the circuit in Fig. 4 a . The signal generator is used to produce a 1000 hertz sine wave. The AC voltmeter and the leads to the verticle input of the oscilloscope are connected across the generators output. By adjusting the Horizontal Sweep time cm and trigger, a steady trace of the sine wave may be displayed on the screen. The trace represents a plot of voltage vs. time, where the vertical deflection of the trace about the line of symmetry CD is proportional to the magnitude of the voltage at any instant of time.