Self Test

 1. (a) A sinusoidal alternating voltage has a peak value of 12 V and a frequency of 50 Hz.  Calculate its time period. 2 (b) Write an equation that would allow you to work out the instantaneous voltages for a time, t, after the voltage went through the 0 point.  Include numerical values in the terms. 2 (c) Use your equation to work out instantaneous values for the voltage at these times.  Show your working out. (i) 4 ms 2 (ii) 7 ms 2 (iii) 18 ms 2
 2. The diagram shows a CRO screen:     The voltage gain is set at 0.2 V cm-1 and the time base is set at 10 ms cm-1. (a) Calculate: (i) The peak to peak voltage; 2 (ii) The RMS voltage; 2 (iii) The frequency. 2 (b) The signal generator producing the sinusoidal wave is now adjusted so that it makes a triangular wave of exactly the same peak voltage and frequency. 2 (i) Work out the new RMS voltage.
 3 An alternating voltage is represented by the equation . Work out: (a) The maximum value of the voltage: 1 (b) The frequency 2 (c) The periodic time 1 (d) What is the angular velocity of the phasor representing this waveform? 2 4. The instantaneous voltage of two alternating voltages are given by these two equations: (a) Sketch a phasor diagram for the two voltage vectors. 4 (b) By accurate drawing or resolution of vectors, obtain expressions for: 7 (i) V1 + V2 (ii) V1 – V2