Basic Electrical Engineering Questions and Answers – Oscillation of Energy at Resonance

This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Oscillation of Energy at Resonance”.

1. The energy stored in the capacitor is of _________ nature.
a) Electrostatic
b) Magnetic
c) Neither electrostatic nor magnetic
d) Either electrostatic or magnetic

Explanation: Since capacitor stores charge in between the plates and energy associated with static charge is of electrostatic nature, so we can say energy stored in the capacitor is of electrostatic nature.

2. The energy stored in the inductor is of _________ nature.
a) Electrostatic
b) Magnetic
c) Neither electrostatic nor magnetic
d) Either electrostatic or magnetic

Explanation: Since inductor stores current which involves moving charge and energy associated with moving charge is of magnetic nature so we can say energy stored in the inductor is of magnetic nature.

3. At resonance, the circuit appears __________
a) Inductive
b) Capacitive
c) Either inductive or capacitive
d) Resistive

Explanation: At resonance, the circuit appears resistive because the capacitive and inductive energies are equal to each other.

4. At resonance, the capacitive energy is ___________ inductive energy.
a) Greater than
b) Less than
c) Equal to
d) Depends on the circuit

Explanation: At resonance, energy stored in the capacitor is equal to energy stored in the inductor because capacitive reactance and inductive reactance are equal at resonance. So, at resonance, capacitive energy is equal to inductive energy.

5. At resonance, electrostatic energy is ___________ the magnetic energy.
a) Greater than
b) Less than
c) Equal to
d) Depends on the circuit

Explanation: At resonance, energy stored in the capacitor is equal to energy stored in the inductor because capacitive reactance and inductive reactance are equal at resonance. The capacitor stores electrostatic energy and the inductor stores magnetic energy hence they are equal.

6. The maximum magnetic energy stored in an inductor at any instance is?
a) E=LIm2/2
b) E=LIm/2
c) E=LIm2
d) E=LIm2*2

Explanation: At any instant, the magnetic energy stored in an inductor is E=LIm2/2, where Im is the maximum current and L is the value of the inductor.

7. The maximum electrostatic energy stored in a capacitor at any instance is?
a) CVm2
b) 1/2*CVm2
c) CVm
d) CVm/2

Explanation: The maximum electrostatic energy stored in a capacitor at any instance is 1/2*CVm2, where C is the capacitance value and Vm is the peak voltage.

8. Q is the ratio of?
a) Active power to reactive power
b) Reactive power to active power
c) Reactive power to average power
d) Reactive power to capacitive power

Explanation: Q is the ratio of the reactive power to the average power. The reactive power is due to the inductance or capacitance and the average power is due to the resistance.

9. Find the value of Q if the reactive power is 10W and the average power is 5W.
a) 10
b) 5
c) 2
d) 1

Explanation: Q is the ratio of the reactive power to the average power.
Q = Reactive power / Average power = 10/5 = 2.

10. Find the reactive power when the average power is 5W and Q=2.
a) 10W
b) 5W
c) 2W
d) 1W

Explanation: Q is the ratio of the reactive power to the average power.
Q = Reactive power / Average power
2 = Reactive power / 5
Reactive Power = 2*5 = 10W.

Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.

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