Question 4.1: A sine wave voltage has a maximum value of 20 V and a freque......

We can find the voltage at any instant of time using:

v = V_{\text{max}} sin (20 t)

where V_{\text{max}} = 20 V and f = 50 Hz.

In (a), t = 2.5 ms, hence:

v = 20 sin (2π × 50 × 0.0025) = 20 sin (0.785)

= 20 × 0.707 = 14.14 V

In (b), t = 15 ms, hence:

v = 20 sin (2π × 50 × 0.0015) = 20 sin (4.71)

= 20 × -1 = -20 V