Question

A coil of 40 henry inductance is connected in series with a resistance of 8 ohm and the combination is joined to the terminals of a 2 volt battery. The time constant of the circuit is:

• A. 20 seconds
• B. 5 seconds
• C. 1/5 seconds
• D. 40 seconds

Hint:

For an RL circuit, the time constant \( \tau \) is the ratio of inductance to resistance.

Answer 1

The Correct Option is B

Step 1: The time constant \( \tau \) of an RL circuit is given by the formula \( \tau = \dfrac{L}{R} \), where \( L \) is the inductance and \( R \) is the resistance.
Step 2: Given \( L = 40 \, \text{H} \) and \( R = 8 \, \Omega \), the time constant is: \[ \tau = \dfrac{40}{8} = 5 \, \text{seconds}. \]
Final Answer: \[ \boxed{5 \, \text{seconds}} \]