A conducting rod of length ℓ and mass m slides without friction on parallel rails in uniform B and is connected to an initially uncharged capacitor C. A constant force F is applied at t=0. Select the correct statements.

Question

G1 Physics · Accepted Answer

Motional emf gives V=Blv, so q=CBlv and i=CBla. Magnetic drag is Bli=B2ℓ²Ca. Therefore F=(m+B2ℓ²C)a, so a is constant and v=Ft/(m+B2ℓ²C). Since q∝v, C and D also follow. Hence A,B,C,D.