(a) When the primary of a transformer is connected to a 120 V AC mains the current in the primary is 18.5 mA. Find the voltage across the secondary when it delivers 1.5 mA current through it, assuming the transformer to be an ideal one. State any one type of energy loss in a transformer.
(b) A rectangular coil of sides .I. and .b. carrying a current lis subjected to a uniform magnetic field `vecB` acting perpendicular to its plane. Obtain the expression for the torque acting on it.

Explanation

(a) Apply `N_s/N_p=V_s/V_p=I_p/I_s`
(b) From the relation `barm=I lb hatn" and Torque "=vecm xx vecB`.