Exam 30: Induction and Inductance

A vertical bar magnet is dropped through the center of a horizontal loop of wire, with its north pole leading. At the instant when the midpoint of the magnet is in the plane of the loop, the induced current in the loop, viewed from above, is:

The figure shows a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, a constant magnetic field between the rails should be in what direction?

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. When the total emf of the combination is 16 V, the rate of change of the current in the larger inductor is:

A rod with resistance R lies across frictionless conducting rails in a constant uniform magnetic field B, as shown. Assume the rails have negligible resistance. The magnitude of the force that must be applied by a person to pull the rod to the right at constant speed v is:

A circular loop of wire rotates about a diameter in a magnetic field that is perpendicular to the axis of rotation. Looking in the direction of the field at the loop the induced current is:

A changing magnetic field pierces the interior of a circuit containing three identical resistors. Two voltmeters are connected as shown. V₁ reads 1 mV across R. V₂ reads the voltage across the other two resistors, which is:

1 weber is the same as:

A 6.0 mH inductor is in a circuit. At the instant the current is 5.0 A and its rate of change is 200 A/s, the rate with which the energy stored in the inductor is increasing is:

The emf developed in a coil X due to the current in a neighboring coil Y is proportional to the:

A 10 turn conducting loop with a radius of 3.0 cm spins at 60 revolutions per second in a magnetic field of 0.50 T. The maximum emf generated is:

A 3.5 mH inductor and a 4.5 mH inductor are connected in parallel. The equivalent inductance is:

As a loop of wire with a resistance of 10 $\Omega$ moves in a non-uniform magnetic field, it loses kinetic energy at a uniform rate of 5 mJ/s. The induced emf in the loop is:

Which statement about eddy currents is false?

If both the resistance and the inductance in an LR series circuit are doubled the new inductive time constant will be:

The diagram shows an inductor that is part of a circuit. The direction of the emf induced in the inductor is indicated. Which of the following is possible?

Faraday's law states that an induced emf is proportional to:

An inductance L, resistance R, and ideal battery of emf are wired in series and the circuit is allowed to come to equilibrium. A switch in the circuit is opened at time t = 0, at which time the current is /R. At any later time t the potential difference across the resistor is given by:

A single loop of wire with a radius of 7.5 cm rotates about a diameter in a uniform magnetic field of 1.6 T. To produce a maximum emf of 1.0 V, it should rotate at:

One hundred turns of insulated copper wire are wrapped around an iron core of cross-sectional area 0.100 m². The circuit is completed by connecting the coil to a 10- $\Omega$ resistor. As the magnetic field along the coil axis changes from 1.00 T in one direction to 1.00 T in the other direction, the total charge that flows through the resistor is:

The unit "henry" is equivalent to: