250+ TOP MCQs on Alternating Current in a Capacitive Circuit and Answers

Basic Electrical Engineering Problems focuses on “Alternating Current in a Capacitive Circuit”.

1. What is the resonance frequency of ac circuit?
A. 1/√LC
B. √(L/C.
C. √LC
D. LC
Answer: A
Clarification: At resonance, X_L=X_C
ωL=1/ωC
ω=1/√LC.

2. What is impedance at resonance?
A. maximum
B. minimum
C. zero
D. cannot be determined
Answer: B
Clarification: At resonance, X_L=X_C
Z²=R²+(X_L-X_C)²
Z=R So Z is minimum at resonance.

3. What is the value of impedance at resonance?
A. X_L
B. X_C
C. R
D. 0
Answer: C
Clarification: At resonance, X_L=X_C
Z²=R²+(X_L-X_C)²
Z=R So Z is minimum at resonance.

4. What is φ in terms of voltage?
A. φ=cos^-1V/V_R
B. φ=cos^-1V*V_R
C. φ=cos^-1V_R/V
D. φ=tan^-1V/V_R
Answer: C
Clarification: Form the voltage triangle, we get cosφ= V_R/V.
Hence φ=cos^-1V_R/V.

5. What is tanϕ for RC circuit?
A. X_C/R
B. X_L/R
C. R/Z
D. Z/R
Answer: A
Clarification: From the impedance triangle, height gives capacitive reactance and base gives resistance.
tanϕ=X_C/R.

6. What is the resonance condition?
A. When X_L>X_C
B. When X_LC
C. When X_L=X_C
D. When X_C=infinity
Answer: C
Clarification: The current is in phase with the voltage when the capacitive reactance is in equal to the inductive reactance. This is known as resonance condition.

7. What is the frequency in resonance condition?
A. Minimum
B. Maximum
C. Cannot be determined
D. Zero
Answer: B
Clarification: At resonance condition, the frequency is maximum since the inductive reactance is equal to the capacitive reactance. X_L=X_C.

Engineering Problems,