Quiz: Electrical Engineering
Each question carries 1 mark.
Negative marking: 1/4 mark
Time: 10 Minute
Q1. A 440 V ,3-phase, 10 pole and 50 Hz synchronous motor delivering a torque of 50/π Nm, delivers a power of
Q2. As compared to a split phase motor, a capacitor start motor has………
(a)Higher running torque
(b)Lower starting torque
(c)Higher starting torque
(d)None of the above
Q3. Which of the following voltmeter has least power consumption?
Q4. What will be the transformation ratio of a 550/110 V, 50 Hz single-phase step-down transformer?
Q5. Diffusion capacitance of a PN junction diode………. with forward bias.
(c)Remains the same
(d)May increase or decrease
Q6. The purpose of guard ring in transmission lines is to…………
(a)Reduce the reactance of the line
(b)Increase the earth capacitance of the lowest unit
(c)Reduce the transmission line losses
(d)Reduce the earth capacitance of the lowest unit
Q7. An RLC series resonance circuit boosts:
Q8. The metal surfaces for electrical resistance welding must be
Q9. The most modern method for food processing is
(d)Eddy current heating
Q10. How many earth pits are there for one transformer in a sub-station?
Sol. Synchronous speed(N_s )=120f/P=(120×50)/10=600 rpm
Sol. Decreasing order of starting torque:
Capacitor start capacitor run > capacitor start > split phase
Sol. Electrostatic type has very low power consumption while induction type has very high-power consumption.
Sol. Turn ratio=N_1/N_2 =V_1/V_2
Transformation ratio=N_2/N_1 =V_2/V_1 =110/550=0.2
Sol. Diffusion capacitance is directly function of applied voltage or current. when forward bias voltage is applied across PN diode, a large number of charges is accumulated near the depletion layer, as a result, large diffusion capacitance occurs,
Sol. The purpose of guard ring in transmission lines is to:
Reduce the earth capacitance of the lowest unit
Equal voltage distribution across each disc
Sol. RLC series resonance circuit:
X_L=X_C and Z=R
As impedance is lower, the current will be maximum.
Sol. Resistance welding is the process of joining metal parts with the application of pressure.
The metal surface should be properly cleaned so that they are free from rust, dust, oil and grease.
Sol. Dielectric heating
Sol. There are minimum four earth pits will be required for any transformer.
2 for its neutral earthing and 2 connections for its body earthing.