NEET2015PhysicsAlternating CurrentActual
An inductor (L=20 H ) , a resistor (R=100 ) and a battery (E=10 ~V ) are connected in series. After a long time, the circuit is short-circuited and then the battery is disconnected. Find the current in the circuit at 1 ms after short circuiting.
Options
- A4.5 10^5 ~A
- B3.2 10⁻⁵ ~A
- C9.8 10⁻⁵ ~A
- D6.7 10⁻⁴ ~A
Correct answer
D. 6.7 10⁻⁴ ~A
Step-by-step solution
The initial current i=i₀= E R = 10 100 =0.10 ~A the time constant, = L R = 20 mH 100 =0.20 ~ms The current at t=1 ~ms is aligned i & =i₀ e^ -t / & =(0.10) e^ ( -1 ~ms 0.20 ~ms ) & =(0.10) e^5=6.7 10⁻⁴ ~A aligned