In figure, a lamp P is in series with an iron-core inductor L. When the switch S is closed, the brightness of the lamp rises relatively slowly to its full brightness than it would do without the inductor. This is due to

Question

G1 Physics · Accepted Answer

Use εₗ=-L(dI/dt), U=½LI², and for mutual induction ε₂=-M(dI₁/dt). Applying the stated geometry/circuit condition gives the induced-emf in L.