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The Sine Wave

Author: N.H. Crowhurst

We have started to talk about alternating (or a-c) voltages, giving them figures in some cases, as we might measure them with a suitable instrument. But there are several ways of measuring alternating voltages and currents. Later on these will cause confusion if we do not get the differences straight now.

A sine wave of 1 volt peak

A pure frequency has a waveform called a sine wave, and is called a sinusoidal wave. If the wave fluctuates between +1 volt and -1 volt from 0 as the starting point, the total change, called the peak-to-peak voltage, is 2 volts. The "swing" each way from the central starting point is called the peak voltage, in this case 1 volt.

When an oscilloscope is used to observe a waveform, it is fairly easy to measure the peak, or peak-to-peak, waveform with a ruler, or by using a calibrated scale in front of the screen. Most meters however, do not measure either peak, or peak-to-peak,voltages.

Waveforms can be measured by graph transparency on an oscilloscope

Last Update: 2010-11-03