26.If a current increases from 0 to 1 A in 0.1 s in coil of 5 mH, then the magnitude of the induced emf will be:

27.A coil of inductance L = 300 mH and resistance R = 140 m? is connected to a constant voltage source. Current in the coil will reach to 50% of its steady value after time t equal to:

28.In the case of charging or discharging of a capacitor RC has units of

29.A coil is wound on a frame of rectangular cross-section. If the linear dimensions of the frame are double and the number of turns per unit length of the coil remains the same, then the self inductance increases by a factor of