Circuit with switch

Question

Answer 1

(1)

Step 1 :

Case (1) :

At , the switch is connected to terminal A.

At , the capacitor acts as open circuit.

Hence the capacitor charges upto 60 V.

Step 2 :

Case (2) :

At , the switch is connected to terminal B.

The voltage across each component is equal to the total circuit voltage.

Solve the equation for current i.

Substitute , and in in the equation.

Apply laplace transform to find current i.

Laplace transform of constant : .

Laplace transform of integral function : .

Apply inverse laplace transform.

Inverse laplace transform : .

The current flowing through the circuit at any moment of time is  A.

Current in series network is same, hence current flowing in the capacitor is A.

Solution :

The current flowing in the capacitor is A.

Answer 2

Step 1:

Find the Voltage across capacitor .

The voltage across each component is equal to the total circuit voltage.

So the volatge across capacitor is .

Volatge across resistor is .

Substitute and in .

Voltage across the capacitor is .

Substitute and in .

Voltage across capacitor is  V.

Solution :

Voltage across capacitor is V.