How is instantaneous voltage at any point on a waveform calculated?

The calculation of instantaneous voltage at any point on a waveform follows the formula involving the maximum voltage (E(max)) and the sine of the angle of rotation. In the context of an alternating current (AC) waveform, the maximum voltage represents the peak amplitude of the sine wave, while the angle of rotation corresponds to a specific point in the waveform's cycle.

By multiplying E(max) by the sine of the angle, you effectively determine the instantaneous voltage at that angle in time. This is foundational in AC circuit analysis, where voltages and currents vary sinusoidally with time. Since the sine function fluctuates between -1 and 1, multiplying it by E(max) allows for the generation of both positive and negative instantaneous voltages, accurately reflecting the alternating nature of AC signals.

The other options inaccurately represent the relationships involving voltage or apply incorrect trigonometric functions that do not conform to the sine wave characteristics. Therefore, the dependence on E(max) and sine is essential for accurate representation in the context of sinusoidal waveforms.