Exam 30: Induction and Inductance

An inductance L, resistance R, and ideal battery of emf are wired in series.A switch in the circuit is closed at time t = 0, at which time the current is zero.At any later time t the emf of the inductor is given by:

A current of 10 A in a certain inductor results in a stored energy of 40 J.When the current is changed to 5 A in the opposite direction, the stored energy changes by:

In each of the following operations, energy is expended.The LEAST percentage of returnable electrical energy will be yielded by:

Which statement about eddy currents is false?

In the diagram, assume that all the magnetic field lines generated by coil 1 pass through coil 2.Coil 1 has 100 turns and coil 2 has 400 turns.Then:

A long narrow solenoid has length ℓ and a total of N turns, each of which has cross-sectional area A.Its inductance is:

A cylindrical region of radius R contains a uniform magnetic field parallel to its axis.The field is zero outside the cylinder.If the magnitude of the field is changing at the rate dB/dt, the electric field induced at a point 2R from the cylinder axis is:

A rod of length L and electrical resistance R moves through a constant uniform magnetic field ; both the magnetic field and the direction of motion are parallel to the rod.The force that must be applied by a person to keep the rod moving with constant velocity is:

A magnet moves inside a coil.Consider the following factors: Which can affect the emf induced in the coil?

Immediately after switch S in the circuit shown is closed, the current through the battery is: