1. Which braking method is the best method for obtaining high braking torque?

A. Regenerative braking
B. Plugging
C. Dynamic braking
D. Rheostatic braking

Answer: B

Plugging is the best braking method among all braking techniques. In plugging the value of the armature current reverses and the mechanical energy is extracted. A very high braking torque is produced in the case of plugging.

2. In which of the following method the polarity of back e.m.f change?

A. Plugging
B. Regenerative braking
C. Dynamic braking
D. Rheostatic braking

Answer: A

In the case of the Plugging braking technique polarity of the back e.m.f voltage changes due to which current direction changes and mechanical, and electrical energy are wasted in the form of heat in resistors.

3. What is the Full form of WRIM?

A. Wound round induction motor
B. World cage induction motor
C. Wolf cage induction motor
D. Squirrel cage inverter motor

Answer: A

WRIM stands for wound round induction motor. WRIM rotor is made up of armature conductors. There are no copper bars or rods involved in it.

4. Calculate the energy stored in the capacitor if the voltage across the capacitor is 20 V and the capacitance value is 2 F.

A. 400 J
B. 200 J
C. 100 J
D. 50 J

Answer: A

The energy stored in the capacitor is .5×C×V2. It is the total amount of energy stored in the capacitor in the steady-state condition.

E = .5×C×V^{2}

= .5×2×20×20 = 400 J.

5. Calculate the energy stored in the inductor if the current value is 4 A and the inductance value is 1 H.

A. 4 J
B. 2 J
C. 8 J
D. 5 J

Answer: C

The energy stored in the inductor is .5×L×I2. It is the total amount of energy stored in the inductor in the steady-state condition.

E = .5×L×I^{2}

= .5×1×4×4 = 8 J.

6. All networks are always circuits.

A. True
B. False

Answer: B

The network is defined as the interconnection of electrical elements that may or may not has a closed path.

The circuit is defined as the interconnection of an element that must have at least one closed path. All networks are not always circuits but vice-versa is true.

7. The Thevenin voltage of a dead circuit is zero volts.

A. True
B. False

Answer: A

In the case of the dead network, there are no independent sources available in the electrical circuit. The Thevenin voltage of the circuit is zero because no force is available to drive the current in the circuit.

8. During the open circuit condition, the current is equal to ______

A. 1 A
B. 0 A
C. 4 A
D. 7 A

Answer: B

During the open circuit condition, the current is equal to zero amperes.

According to Ohm’s law, I = V/R = 0 A.

The value of the voltage can be positive, negative, or zero.

9. The minimum value of the impedance in the case of the series RLC network is ___________

A. R
B. 0
C. Xl
D. Xc

Answer: A

The minimum value of the series impedance in the case of the series RLC network is R. During resonance condition

Xl = Xc

Z = (R^{2}+(Xl-XC)^{2}).5 = R.

10. Calculate the quality factor for the purely inductive coil.

A. infinite
B. 10
C. 3
D. 6

Answer: A

The quality factor is defined as the ratio of the reactive power to the active power consumed.

The purely inductive coil always absorbs reactive power. The value of active power consumed is 0.