104 Single-phase a.c. circuits8 Determine the form factor of an alternating waveform whose rms value is
50 and whose ~ average value is 45.
9 Give the relationship between the voltage and current in a purely resistive
a.c. circuit.10 Calculate the inductive reactance of a coil whose inductance is 60 mH
when it is connected to a supply of frequency 400 Hz.
11 A capacitor of capacitance 0.1 ~F is connected to a 50 Hz supply.
Calculate its capacitive reactance.
12 Give the unit of impedance.
13 Determine the phase angle of a coil having a resistance equal to half its
inductive reactance.
14 Determine the impedance of a coil having a resistance and reactance both
equal to 20 1).
15 Calculate the impedance of a circuit consisting of a capacitor in series with
the coil of Question 14 if the capacitive reactance of the capacitor is (a)
10 ~ and (b) 20 1~.
16 Describe an Argand diagram.
17 Express j7 in its simplest form.
18 In which quadrant does (-6 - j5) lie?
19 Determine the magnitude and phase angle of the phasor represented by
v = (10 - j15).20 Express 25/_30 ~ in rectangular coordinate form.
21 Express 3 + j4 in polar coordinate form.
22 An a.c. circuit consists of a resistor of 5 f~ resistance in series with an
inductive reactance of 6 fl. Express the impedance of this circuit in j form.
23 A resistance of 10 l-I is connected in parallel with a capacitive reactance of
25 fl. Express the admittance of this circuit in j form.
24 Give an expression using the j-notation which relates real power, reactive
power and apparent power.
25 An RLC series circuit has R = 5 12, XL = 6 ll and Xc = 10 12. A current
given by (5 + j0) A flows through the circuit. Determine: (a) the apparent
power; (b) the real power; (c) the reactive power; (d) the power factor; (e)
the applied voltage in j-form.