Exam 20: Induced Voltages and Inductance

A bar magnet is falling through a loop of wire with constant velocity.The north pole enters first.As the south pole leaves the loop of wire,the induced current (as viewed from above)will be

If a bar magnet is falling through a loop of wire,the induced current in the loop of wire sets up a field which exerts a force on the magnet.This force between the magnet and the loop will be attractive when

Three loops of wire,one circular,one rectangular,and one square,are made from identical lengths of wire.If the loops are in the same increasing magnetic field perpendicular to the plane of the coils,which loop has the greatest induced emf?

The back emf in an electric motor is its maximum value under which condition?

By what factor is the self-inductance of an air solenoid changed if only its cross-sectional area,A,multiplied by eight?

In a circuit made up of inductor,resistance,ammeter,battery and switch in series,at which of the following times after the switch is closed is the rate of current increase greatest?

A 41-turn square coil of area 0.074 m² and a 123-turn circular coil are both placed perpendicular to the same changing magnetic field.The voltage induced in each of the coils is the same.What is the area of the circular coil?

A rectangular loop (area = 0.250 m²)turns in a uniform magnetic field with B = 0.210 T.At an instant when the angle between the magnetic field and the normal to the plane of the loop is π/2 rads and increasing at the rate of 0.530 rad/s,what is the magnitude of the emf induced in the loop?

The current in a coil with a self-inductance of 2.4 mH increases from 0 to 2.66 A in a tenth of a second.What is the induced emf in the coil?

A uniform 8.00-T magnetic field passes perpendicularly through the plane of a wire loop 0.320 m² in area.What flux passes through the loop?

The magnetic field going through a stationary circular loop increases from zero to 5 T in a certain time t.The induced current in the loop will depend on the radius of the loop,r,the resistance of the loop,R,and the time,t.If two of these stay constant,the induced current can be directly proportional to