Question

An RC-circuit is attached to a 12.00-volt battery. Itâ s resistance is 6 ohms and its relaxation time is 3.03 microseconds. Before continuing, carefully calculate the time when the current was 1.303 A in your notes. Remember units and significant figures! Hey, what would your reaction have been if I had told you that the current was 3 ampere?

A. What unit will you be using for your answer?
B. How many significant digits should your answer have?
C. When did the circuit have this current?

Answer 1

Current in a capacitor at any time t is given by

(1)

Where, I0 = Maximum current in the circuit ,i.e current at t = 0s.

= relaxation time of the circuit

Given that:

At t = 0s, Capacitor behaves as a circuit. So,

Putting all valuese in equation (1), we get

(2)

So, at t = 1.415, current in the circuit is 1.303A.

Part(A). We will be using the answer when maximum current in the circuit is 2.0A.

Part(B). One significant digit.

Part(C). Since maximum current in the circuit is 2A. So, the circuit never have 3A current.