Question

For given $L-R$ circuit, growth of current as function of time $t$ is shown in graph. Which of the following option represents value of time constant most closely for the circuit?

• A. $0.7s$
• B. $1s$
• C. $2.4s$
• D. $0.4s$

Answer 1

The correct option is B $1s$

In one time constant $63$% change occurs in the value of current. The $63$% of maximum current is $1.26A$. If is obvious from graph, the current $1.26A$ corresponds to time which is slightly greater than $0.9s$. Hence, option having $1s$ is most appropriate.