QJEEM15Phcc27: JEE Main 2015 Physics - Class 12 JEEM15Phcc27 Solution: An inductor ( L = 0.03 H ) and a resistor ( R = 0.15 k Ω ) are…

Question

Verified Solution • 2025–26 Session moderate

An inductor

(L = 0.03

H)

and a resistor

(R = 0.15 k Ω)

are connected in series to a battery of

15 V

E M F

in a circuit shown below. The key

K_{1}

has been kept closed for a long time. Then at

t = 0

,

K_{1}

is opened and key

K_{2}

is closed simultaneously. At

t = 1

m s,

the current in the circuit will be :

(e^{5} ≅ 150)

Accepted Answer

I (0) = \frac{15 \times 100}{0.15 \times 10^{3}} = 0.1 A

I (\infty) = 0

I (t) = [I (0) - I (\infty)] e^{\frac{- t}{L / R}} + i (\infty)

I (t) = 0.1 e^{\frac{- t}{L / R}} = 0.1 e^{\frac{R}{L}}

I (t) = 0.1 e^{\frac{0.15 \times 1000}{0.03}} = 0.67 m A

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