250+ TOP MCQs on Circuit Elements in the S-Domain and Answers

Network Theory Multiple Choice Questions on “Circuit Elements in the S-Domain”.

1. The resistance element __________ while going from the time domain to frequency domain.
A. does not change
B. increases
C. decreases
D. increases exponentially

Answer: A
Clarification: The s-domain equivalent circuit of a resistor is simply resistance of R ohms that carries a current I ampere seconds and has a terminal voltage V volts-seconds. The resistance element does not change while going from the time domain to the frequency domain.

2. The relation between current and voltage in the case of inductor is?
A. v=Ldt/di
B. v=Ldi/dt
C. v=dt/di
D. v=di/dt

Answer: B
Clarification: Consider an inductor with an initial current I_o. The time domain relation between current and voltage is v=Ldi/dt.

3. The s-domain equivalent of the inductor reduces to an inductor with impedance?
A. L
B. sL
C. s²L
D. s³L

Answer: B
Clarification: If the initial energy stored in the inductor is zero, the equivalent circuit of the inductor reduces to an inductor with impedance sL ohms.

4. The voltage and current in a capacitor are related as?
A. i=Cdt/dv
B. v=Cdv/dt
C. i=Cdv/dt
D. v=Cdt/dv

Answer: C
Clarification: Consider an initially charged capacitor and the initial voltage on the capacitor is V_o. The voltage current relation in the time domain is i=Cdv/dt.

5. The s-domain equivalent of the capacitor reduces to a capacitor with impedance?
A. sC
B. C
C. 1/C
D. 1/sC

Answer: D
Clarification: The s-domain equivalent of the capacitor can be derived for the charged capacitor and it reduces to an capacitor with impedance 1/sC.

6. From the circuit shown below, find the value of current in the loop.
A. (V/R)/(s+1/RC.
B. (V/C./(s+1/R)
C. (V/C./(s+1/RC.
D. (V/R)/(s+1/R)

Answer: A
Clarification: Applying Kirchhoff’s law around the loop, we have V/s=1/sC I+RI. Solving above equation yields I=CV/(RCS+1)=(V/R)/(s+1/RC..

7. After taking the inverse transform of current in the circuit shown below, the value of current is?

A. i=(V/C.e^-t/R
B. i=(V/C.e^-t/RC
C. i=(V/R)e^-t/RC
D. i=(V/R)e^-t/R

Answer: C
Clarification: We had assumed the capacitor is initially charged to V_o volts. By taking the inverse transform of the current, we get i=(V/R) e^-t/RC.

8. The voltage across the resistor in the circuit shown below is?

A. Ve^t/R
B. Ve^-t/RC
C. Ve^-t/R
D. Ve^t/RC

Answer: B
Clarification: We can determine the voltage v by simply applying the ohm’s law from the circuit. And applying the Ohm’s law from the circuit v = Ri = Ve^-t/RC.

9. The voltage across the resistor in the parallel circuit shown is?

A. V/(s-1/R)
B. V/(s-1/RC.
C. V/(s+1/RC.
D. V/(s+1/C.

Answer: C
Clarification: The given circuit is converted to parallel equivalent circuit. By taking the node equation, we get v/R+sCv=CV. Solving the above equation, v=V/(s+1/RC..

10. Taking the inverse transform of the voltage across the resistor in the circuit shown below is?

A. Ve^-t/τ
B. Ve^t/τ
C. Ve^tτ
D. Ve^-tτ

Answer: A
Clarification: By taking the inverse transform, we get v=Ve^-t/RC=Ve^-t/τ, where τ is the time constant and τ = RC. And v is the voltage across the resistor.