up Sepcial current

A step-up transfomer operates on a 220 volt line and supplies to load, a current of 2A. The ratio of primary and secondary winding is 1 : 25. Calculate secondary voltage, primary current and power output, if efficiency is 80%

A galvanometer with its coil resistance 25 Omega requires a current of 1 mA for its full deflection. In order to construct an ammeter to read up to a current of 2A, the approximate value of the shunt resistance should be :

A solenoid of length 0.5 m has a radius of 1 cm and is made up of 500 turns. It carries a current of 5 A. The magnetic field inside the solenoid is

Two long parallel conductors are carrying currents in the same direction as shown in the figure. The upper conductor A carrying a current of 100 A is held firmly in position. The lower conductor B carries a current of 50 A and free to move up and down. The linear mass density of the lower conductor is 0.01 kg/m.

Assertion (A): Safety fuses are made up of materials having a low melting point. Reason (R): Safety fuses should be resistant to electric current

When a current I is set up in a wire of radius r, the drift velocity is v_(d) . If the same current is set up through a wire of radius 2r, the drift speed will be