What are the different voltages in AC and what does rms mean ?
With AC the voltage is constantly changing and so as to get a single number to use for discussion and calculation purposes, engineers use normally the root of the mean of the square (RMS) voltage, or occasionally either the peak, or the peak to peak voltage. With a pure sinusoidal waveform the voltage that is generally discussed is the RMS voltage because this is equivalent to the DC voltage that produces the same heating effect for a given current. So 240V RMS is equivalent to 339 V peak, or 679 V peak to peak and can be written as 240 Vrms. (the formula is Vrms = Vmax / √2). This is illustrated in Figure 1 below which shows a sinusoid varying about a neutral, and which can also be drawn as a vector with a single arrow pointing away from neutral. When a load is connected in an AC network the electrons oscillate backwards and forwards rather than flowing through it as they do in a DC network. Broadly speaking current is related to voltage and resistance by the formula V=IR and so in a
