Electro Magnetic Induction And Alternating Currents Question 602
Question: An inductance L and a resistance R are first connected to a battery. After some time the battery is disconnected but L and R remain connected in a closed circuit. Then the current reduces to 37% of its initial value in [MP PMT 1994]
Options:
A) RL sec
B) $ \frac{R}{L}sec $
C) $ \frac{L}{R}sec $
D) $ \frac{1}{LR}sec $
Show Answer
Answer:
Correct Answer: C
Solution:
When battery disconnected current through the circuit start decreasing exponentially according to $ i=i_{0}{{e}^{-Rt/L}} $
Þ $ 0.37i_{0}=i_{0}{{e}^{-Rt/L}} $
Þ $ 0.37=\frac{1}{e}={{e}^{-Rt/L}} $
Þ $ t=\frac{L}{R} $
