Electro Magnetic Induction And Alternating Currents Question 162
Question: A coil of inductance 8.4 mH and resistance $ 6\Omega $ is connected to a 12 V battery. The current in the coil is 1.0 A at approximately the time
Options:
A) 500s
B) 25s
C) 35ms
D) 1ms
Show Answer
Answer:
Correct Answer: D
Solution:
-
Using $ I=I_{0}(1-{{e}^{-t/\tau }}) $
But $ I_{0}=\frac{V}{R} $
and $ \tau =\frac{L}{R} $
$ \therefore I=\frac{V}{R}(1-{{e}^{-Rt/L}})=\frac{12}{6}[ 1-{{e}^{-6t/8.4\times {{10}^{-3}}}} ] $ =1 (given)
$ \therefore t=0.97\times {{10}^{-3}}s\approx 1ms $
