Exams › JEE Main › Physics
A coil having a resistance of 50 Ω is joined to a 5.0 V battery. After 0.1 s from the moment of connection, the current through the coil becomes 60 mA. What is the inductance of the coil?
- 5.5 H
- 1.5 H
- 2.5 H
- 9.5 H
Correct answer: 5.5 H
Solution
Final current I0 = V/R = 5/50 = 0.1 A. Using i = I0(1 - e^(-Rt/L)): 0.06 = 0.1(1 - e^(-5/L)) -> e^(-5/L) = 0.4 -> 5/L = ln(2.5) = 0.916 -> L = 5.46 H ~ 5.5 H.
Related JEE Main Physics questions
- A metallic ring is kept in a horizontal position, and a bar magnet is released so that it falls through the ring with its length aligned along the ring’s axis. The magnet’s acceleration while falling is
- A coil has resistance 10 Ω, and the magnetic flux linked with it changes with time according to ϕ = 4t² + 2t + 1 (in weber). The current induced in the coil at t = 1 s is
- Two coils are kept near one another. The mutual inductance of the coil pair depends on
- A conducting rod of length ℓ is attached to a string of length 2ℓ and is rotated on a horizontal table about the fixed end of the string with angular speed ω. If a uniform magnetic field B acts vertically through the region, what is the induced emf between the two ends of the rod?
- A pair of coils, each having N turns, has mutual inductance M henry. If the current in one coil changes from 1 ampere to zero in time t seconds, what is the induced emf per turn in the other coil, in volts?
- A boat travels straight toward the east in a place where Earth’s magnetic field is horizontal, points due north, and has magnitude 5.0 × 10⁻⁵ N A⁻¹ m⁻¹. A 2 m long vertical antenna is mounted on the boat. If the boat’s speed is 1.50 m s⁻¹, what emf is induced across the antenna wire?
⚔️ Practice JEE Main Physics free + battle 1v1 →