In Fig. (a), a solenoid produces a magnetic field increasing into the page. The induced emf in the surrounding conducting loop lights bulbs A and B. In Fig. (b), points P and Q are shorted. After the short is inserted:

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 Bulb A goes out, bulb B gets brighter.