AC revision Question

1. (a) (i) Distinguish between peak value and root mean square value of alternating current. (3 marks) REVISION QUESTIONS FOR A.C CIRCUITS 2. (a) Define resonant frequency in an ac circuit. (1 mark) (i) reactance of the capacitor. (2 marks) (ii) peak value of current in the circuit. (2 marks) (iii) State the advantage of using a capacitor instead of a resistor in an electrical network. (1 mark) (c) Explain why alternating current apparently flows through a capacitor while direct current does not. (4 marks) (d) (i) A current I = Io sin 2πft is passed through a resistor of resistance R ohms. Derive an expression for the average power expended in the device. (3 marks) “The day you plant the seed is not the day you eat the fruit” (c) With the aid of a labelled diagram describe how an attraction type of moving iron ammeter can be used to measure current. (5 marks) (ii) The current in (i) is subjected to a series combination of a pure capacitor of capacitance C and a pure inductor of inductance L, and the circuit resonates at frequency fo. Derive the expression for fo. (i) What is the meaning of the term pure inductor? (1 mark) (ii) Find the reactance of the inductor. (3 marks) (iii) Determine the root mean square voltage of the inductor. (3 marks) (b) An alternating current I = 2.0 sin 120πt is passed through a pure inductor of inductance 0.4 H. (d) A capacitor is connected across a 200 Hz alternating supply with a peak of 100 V, the maximum amount of charge on the capacitor in ea