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Q19. For the network shown in Fig.Q1 calculate each of the following:

(a) The current drawn from each battery;

(b) The potential difference across the 40Ω resistor and across the 50Ω resistor;

(c) The power dissipated in the 60Ωresistor.

Q1. The V/I characteristic of a non-linear resistor is shown in Table Q2.

This non-linear resistor is connected in series with a paralleled pair of resistors of 40 kW and 60 kW and the overall circuit is supplied at 120 V d.c. Determine graphically or otherwise:

(a) The current in the non-linear resistor;

(b) The effective resistance of the non-linear resistor;

(c) The current in the 40 kW resistor.

Q12. Fig Q3 shows a single stage transistor amplifier. The voltage between base and emitter is 0.3 V and the d.c. voltage at the output terminals is 8 V.

(a) Calculate EACH of the following, assuming the base current is small enough to be neglected:

(i) The voltage between emitter and collector;

(ii) The power developed in the 150Ωresistor;

(iii) The power dissipated in the transistor.

(b) Sketch the circuit diagram and show the additional components needed to make the amplifier suitable for amplifying small a.c. signals.

Q12. For the circuit shown in Fig Q4, calculate EACH of the following:

(a) The supply current;

(b) The power factor;

(c) The voltages V₁ and V₂ and their respective phase angles to the supply current.

Q14. Three identical delta connected coils each comprising both resistance and inductance draw a total power of 1.2 kW at a power factor of 0.8 from a 440 V, 50 Hz three phase supply.

Calculate EACH of the following:

(a) The current in each coil;

(b) The resistance and inductance of each coil;

(c) The power absorbed if the three coils are now reconnected in star to the same supply.