Discharge of Capacitor MCQ [Free PDF] – Objective Question Answer for Discharge of Capacitor Quiz

11. If the switch is closed at t = 0, what is the current in the circuit?

cr networks q4

A. 0A
B. 10A
C. 20A
D. Infinity

Answer: B

As soon as the switch is closed at t = 0, the capacitor acts as a short circuit. The current in the circuit is:

I = V/R = 100/10 = 10A.

 

12. Calculate the voltage across the capacitor at t = 0.

Calculate the voltage across the capacitor at t=0.

A. 0V
B. 10V
C. 20V
D. Infinity

Answer: A

When the switch is closed at t = 0, the capacitor has no voltage across it since it has not been charged. The capacitor acts as a short circuit and the voltage across it is zero.

 

13. Calculate di(0)/dt if the switch is closed at t = 0.

Calculate the voltage across the capacitor at t=0.

A. -9.9A/s
B. -10A/s
C. 0A/s
D. -0.1A/s

Answer: D

Applying KVL to the given circuit, we get:

i = i0e-t/RC  = (100/10)e-t/100

i = 10 e-t/100

di/dt = -(10/100) e-t/100

di(0)/dt = -0.1A/s.

 

14. Calculate d2i(0)/dt2 from the given circuit.

Calculate the voltage across the capacitor at t=0.

A. 10-6A/s2
B. 10-3A/s2
C. 106A/s2
D. 103A/s2

Answer: B

Applying KVL to the given circuit, we get:

100+10i(0)+1/10 × ∫(i(0)dt) = 0

Differentiating once, we get:

10di(0)/dt+1/10 × i.

Differentiating once again, we get:

10d2i(0)/dt2+10di(0)/dt = 0.

Substituting the values of di/dt from the previous explanation, we get d2i(0)/dt2 = 10-3A/s2.

 

15. The current equation for the given circuit is?

Calculate the voltage across the capacitor at t=0.

A. i = 10e(-0.01)t A
B. i = 10e(0.01)t A
C. i = 10e(-0.001)t A
D. i = 100e(-0.01)t A

Answer: A

The KVL equation is:

100+10i(0)+1/10 × ∫(i(0)dt) = 0

On applying a Laplace transform to this equation, we get:

100/s = I(s)/10s+10I(s)

Solving the equation, we get:

i = 10e(-0.01)t A.

 

16. The expression for the current in an RC circuit is?

A. i = (V/R)et/RC
B. i = (V/R)e-t/RC
C. i = (V/R)(1-e-t/RC)
D. i = (V/R) (1-et/RC)

Answer: B

Applying KVL to the given circuit, we get:

i = i0e-t/RC  = (100/10)e-t/100

i = 10 e-t/100.

 

17. What is the voltage in the resistor as soon as the switch is closed at t = 0.

What is the voltage in the resistor as soon as the switch is closed at t=0.

A. 0V
B. Infinity
C. 220V
D. Insufficient information provided

Answer: C

As soon as the switch is closed at t = 0, there is no charge in the capacitor, hence the voltage across the capacitor is zero and all the 220V voltage is the voltage across the resistor.

 

18. Work done in charging a capacitor is ____________

A. QV
B. 1⁄2QV
C. 2QV
D. QV2

Answer: B

We know that work done = Q2/2C.

Substituting C as Q/V, we get work done = Q/2V.

 

19. Energy stored in a 2000mF capacitor charged to a potential difference of 10V is?

A. 100J
B. 200J
C. 300J
D. 400J

Answer: A

From the expression of Capacitor energy

WD = CV2/2 = 100J.

 

20. When do we get maximum energy from a set of capacitors?

A. When they are connected in parallel
B. When they are connected in series
C. Both in series and parallel
D. Insufficient information provided

Answer: A

We get maximum energy when capacitors are connected in parallel because the equivalent capacitance is larger than the largest individual capacitance when connected in parallel. The relation between capacitance and energy is:

Energy = CV2/2, hence as the capacitance increases, the energy stored in it also increases.

Scroll to Top