Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
Concepts Of Physics MCQ Edition [Volume 2]PhysicsElectromagnetic Induction

An LR circuit has a time constant of 40 ms . The circuit is connected at t = 0 and the steady-state current is found to be 2.0 A . Determine the current at t = 20 ms .

Options

  1. A1.73 A
  2. B1.21 A
  3. C0.79 A
  4. D0.39 A

Correct answer

C. 0.79 A

Step-by-step solution

The growth of current in an LR circuit is given by the equation: I(t) = I₀ (1 - e^ -t/ ) Given: Time constant, = 40 ms Steady-state current, I₀ = 2.0 A Time, t = 20 ms Substituting the values into the equation: I = 2.0 (1 - e^ -20/40 ) I = 2.0 (1 - e^ -0.5 ) Using the value e^ -0.5 0.6065 : I = 2.0 (1 - 0.6065) I = 2.0 0.3935 I = 0.787 A 0.79 A

Practice Electromagnetic Induction on Quantrex Academy →

More from Electromagnetic Induction

List-I contains four conducting loops lying in the XY plane, as shown in the figures. The loops are rotating about Z axis passing through the point O with time period T in clockwis 2026A 30 cm long solenoid has 10 turns per cm and area of 5 cm ^2 . The current through the solenoid coil varies from 2 A to 4 A in 3.14 s. The e.m.f. induced in the coil is 10⁻⁵ V. Th 2026A square loop of side 2 cm is placed in a time varying magnetic field with magnitude as B = 0.4 (300t) Tesla. The normal to the plane of loop makes an angle of 60° with the field. 2026An inductor of inductance 10 mH having resistance of 100 , is connected to battery of E.M.F. 1.0 V through a switch as shown in the figure below. After switch is closed, the ratio 2026A metal rod of length L rotates about one end at origin with a uniform angular velocity . The magnetic field radially falls off as B(r) = B₀ e^ - r ; being a positive constant. The 2026A circular loop of radius 20 cm and resistance 2 is placed in a time varying magnetic field B = (2t^2 + 2t + 3) T . At t = 0 , for the plane of the loop being perpendicular to the 2026In the given circuit below inductance values of L₁ , L₂ and L₃ are same. The magnetic energy stored in the entire circuit is (U_t) and that stored in the L₂ inductor is (U_l) . U_t 2026A circular current loop of radius R is placed inside square loop of side length L(L >> R) such that they are co-planar and their centers coincide. The permeability of free space is 2026 Full Electromagnetic Induction list All Concepts Of Physics MCQ Edition [Volume 2] PYQs