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Q.73

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Found in: Page 794

### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

Book edition 4th
Author(s) Randall D. Knight
Pages 1240 pages
ISBN 9780133942651

# The capacitor in FIGURE begins to charge after the switch closes at.a. What is a very long time after the switch has closed?b. What is in terms of E,R, and C?c. In this circuit, does ? Explain.d. Find an expression for the current I at time t. Graph I from to

a. The value of is .

b. The value of is .

c. In this circuit

d. The expression for the current is .

See the step by step solution

## Part (a) Step 1: Given information.

We need to find expression for the current I at time t.

## Part (a) Step 2: Explanation

If the battery starts to charge the capacitor. After a long time, it is fully charged and the potential difference across the capacitor is the same for the

We need to find.

## Part (b) Step 2 : Simplify

If it is fully charged, on the plates of the maximum . This will be found at the voltage

## Part (c) Step 2: Clarification

When the switch is closed, current starts to flow from the battery to the capacitor, so the charges on the capacitor increases, The change of the charge is positive.

## Part (d) Step 1 : Given Information.

Finding the expression of the current I at time t.

## Part (d) Step 2 :

The capacitor discharge and the current flow through the resistors. To charge it flows through the circuit in time t

t is the time and is the time constant. The change of the charge with time, so we use the expression from part (c) to get I

The capacitor discharge and the current flow through the two resistors when the switch is off. The time taken to discharge the capacitor is called the time constant and it is given the equation in the form

Plug the expression for and into equation (2) to get I by

The time decreases exponentially.