CGPET 2021 Solved Paper

Initially, the magnet moves towards the coil, the magnetic flux (ϕB) increases and due to this, the negative induced emf [e=

−dϕ

dt

] is also increases.
When the magnet moves inside the coil, the increase in ϕB goes up to maximum value. This shows that the emfe induced reaches at its maximum negative value. After this, ϕB starts decreasing. Thus, e becomes positive and its magnitude starts increasing, i.e. there is a change in polarity of mathrm‌emf(F) as the magnet passes through other side of coil.
Hence, correct variation of induced emf with time t is shown in the graph given in option (b).