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Q10. Determine EACH of the following, for the circuit shown in Fig Q1:

(a) The current in the 1 kΩ moving coil meter;

(b) The value of a resistor to be placed in series with the meter to reduce the current in the meter to 1 mA.

Q11. A capacitor ‘C’ is connected in series with a resistor of 2 kΩ to a 150 V d.c. supply. When the capacitor is fully charged the energy stored is 4.5 J. Determine EACH of the following:

(a) The value of the capacitor;

(b) The time taken for the capacitor to charge to half the supply voltage;

(c) The value of resistance to be added in series to increase the time found in part (b) above to 1.2 secs.

Q6. Fig Q3 shows a two-stage transistor amplifier using high gain transistors whose base currents are small enough to be neglected. The voltage between base and emitter for transistor T₁ is 0.4 V. and for transistor T₂ it is 0.6 V. Determine EACH of the following:

(a) The collector current for T₁;

(b) The voltage at the base of T₂;

(c) The collector current for T₂;

(d) The steady state value of V_out

Q5. A capacitor connected in series with a resistor is tested on 240 V 50 Hz and the current is found to be 3.6 A. When the frequency is raised to 100 Hz the current increases to 4.8 A.

Determine EACH of the following:

(a) The values of the resistor and the capacitor;

(b) The power factor of the circuit at 50 Hz;

(c) The value of an inductor which, when connected in series with the pair, will give the same current of 3.6 A at 50 Hz but with a lagging power factor equal to the value obtained in part (b).

Q6. A 3ph 440 V 60 Hz 8 pole induction motor runs at a power factor of 0.85 lag and drives a load of 8 kW at a speed of 14.4 rev/sec. The stator loss is 1 kW and the rotational losses (windage and friction) amount to 0.8 kW. Calculate EACH of the following:

(a) The synchronous speed;

(b) The rotor copper loss;

(c) The input power to the motor;

(d) The motor current.