Exam 30: Induction and Inductance

A uniform magnetic field makes an angle of 30 $\degree$ with the z axis. If the magnetic flux through a 1-m² portion of the xy plane is 5 Wb then the magnetic flux through a 2-m² portion of the same plane is:

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- $\pi$ 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 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?

A 2-T uniform magnetic field makes an angle of 30 $\degree$ with the z axis. The magnetic flux through a 3-m² portion of the xy plane is:

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:

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

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:

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

A changing magnetic field pierces the interior of a circuit containing three identical resistors. Two voltmeters are connected to the same points, as shown. V₁ reads 1 mV. V₂ reads:

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

A long straight wire is in the plane of a rectangular conducting loop. The straight wire initially carries a constant current i in the direction shown. While the current i is being shut off, the current in the rectangle is:

1 weber is the same as:

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:

An inductance L and a resistance R are connected in series to an ideal battery. A switch in the circuit is closed at time 0, at which time the current is zero. The energy stored in the inductor is a maximum:

An inductor with inductance L and an inductor with inductance 2L connected in parallel. When the rate of change of the current in the larger inductor is 2000 A/s the rate of change of the current in the smaller is:

An 8.0-mH inductor and a 2.0- $\Omega$ resistor are wired in series to a 20-V ideal battery. A switch in the circuit is closed at time 0, at which time the current is zero. Immediately after the switch is thrown the potential differences across the inductor and resistor are:

An inductance L and a resistance R are connected in series to an ideal battery. A switch in the circuit is closed at time 0, at which time the current is zero. The rate of increase of the energy stored in the inductor is a maximum:

A cylindrical region of radius R contains a uniform magnetic field, parallel to its axis, with magnitude that is changing linearly with time. If r is the radial distance from the cylinder axis, the magnitude of the induced electric field inside the cylinder is proportional to:

In the experiment shown:

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