Q3. For the network shown in Fig Q1 calculate EACH of the following:
(a) The currents I1, I2 and I3;
(b) The p.d across the 100 Ω resistor;
(c) The power dissipated in the 8 Ω resistor.
Q6. In the two-stage voltage amplifier shown in Fig Q3, both the npn and pnp transistors have high current gains and their leakage currents may be neglected. Transistor T1 has a base-emitter volt drop of 0.7 V and transistor T2 has a base emitter drop of 0.3 V. Calculate EACH of the following:
(a) The voltage between the collector and emitter for each transistor;
(b) The power dissipated in each transistor.
Q3. A coil of inductance 0.1 H has a power factor of 0.7 and is connected in parallel with a capacitor ‘C’ across 120 V 60 Hz supply. Calculate EACH of the following:
(a) The resistance of the coil;
(b) The value of ‘C’ if the total current is 4 A at p.f. 0.4 leading;
(c) The power dissipated by the combined circuit;
(d) The kVA for the combined circuit.
Q8. A three-phase star connected load has three identical legs each comprising a 40 Ω resistor in series with a 100 μF capacitor. It is supplied at 415 V, 50 Hz from a three-wire supply.
Calculate EACH of the following:
(a) The current in each phase;
(b) The current in each phase if due to a fault the red phase lead becomes disconnected;
(c) The current in each phase if the red phase becomes short circuited.
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