CBSE Class 12 Physics Electromagnetic Induction Solved Examples

CBSE Class 12 Physics Electromagnetic Induction Solved Examples. Please refer to the examination notes which you can use for preparing and revising for exams. These notes will help you to revise the concepts quickly and get good marks.

Ex.1 A square loop ACDE of area 20 cm2 and resistance 5 W is rotated in a magnetic field B = 2T through 180°
(a) in 0.01 s and (b) in 0.02 s.
Find the magnitude of e, i and Δq in both the cases.
Sol.: Let us take the area vector S perpendicular to plane of loop inwards. So initially, S ↑↑ B and when it is rotated by 180°, S ↑↓ B. Hence, initial flux passing through the loop,

Ex.2 A coil of area 2 m² is placed in magnetic field of which varies as B = (2t² + 2) T with are vector in the direction of B. What is the magnitude of induced emf at t = 1 sec.

Sol.: Angle between area vector and magnetic field is θ = 0

Ex.3 A current i = 3.36 (1 + 2t) × 10^–2 A increases at a steady rate in a long straight wire. A small circular loop of radius 10^–3 m has its plane parallel to the wire and is placed at a distance of 1 m from the wire. The resistance of the loop is 8.4 × 10^–4Ω. Find the magnitude and the direction of the induced current in the loop.

Sol.: The situation is shown in figure . The field due to straight wire at the center of loop

As due to increase in current in the wire the flux linked with the loop will increase, so in accordance with Lenz’s law the direction of current induced in the loop will be inverse of that in wire, i.e., anticlockwise.

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