Question

the variation of the induced e.m.f. ξ with time t, as follows:

t₁ as the time when the field just enters the loop. t₂ as the time when the loop is fully inside the field, and t₃ as the time when the field just completely leaves the loop.

• A. Shows ξ starting at zero, increasing linearly to a positive value between t₁ and t₂, then decreasing linearly back to zero between t₂ and t₃.
• B. Shows ξ starting at zero, increasing linearly to a positive value at t₁, staying constant at this positive value until t₂, and then decreasing linearly back to zero at t₃.
• C. Shows ξ starting at zero, jumping to a positive constant value at t₁, staying constant until t₃, and then dropping back to zero.
• D. Shows ξ starting at zero, increasing with a curve to a positive maximum before t₂, and then decreasing with a curve back to zero after t₂ and before t₃, resembling a sinusoidal pulse.

Answer 1

Answer: (A)

Graph A (Option A)

Answer 2

Explanation:
The induced emf ξ is proportional to the rate of change of magnetic flux. As the magnetic field region enters the loop (from t₁ to t₂) and exits the loop (from t₂ to t₃), the flux through the loop changes linearly—resulting in a linear rise and fall in emf. When the loop is completely inside the region (between t₂ and t₃), the flux is constant, so no emf is induced. This behavior matches Graph A.