Exam 30: Induction and Inductance

A merry-go-round has an area of 300 m² and spins at 2 rpm about a vertical axis at a place where the Earth's magnetic field is vertical and has a magnitude of 5 * 10^-5 T. The emf around the rim is:

A circular loop of wire is positioned half in and half out of a square region of constant uniform magnetic field directed into the page, as shown. To induce a clockwise current in this loop:

As a loop of wire with a resistance of 10 $\Omega$ moves in a constant non-uniform magnetic field, it loses kinetic energy at a uniform rate of 5.0 mJ/s. The induced current in the loop is:

The normal to a certain 1.0 m² area makes an angle of 60 $\degree$ with a uniform magnetic field. The magnetic flux through this area is the same as the flux through a second area that is perpendicular to the field if the second area is:

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 loop is:

A cylindrical region of radius R = 3.0 cm contains a uniform magnetic field parallel to its axis. If the electric field induced at a point R/2 from the cylinder axis is 4.5 *10^-3 V/m the magnitude of the magnetic field must be changing at the rate of:

Two coils have a mutual inductance of 3.5 mH. If the current in one coil is changing at a rate of 4.8 A/s, what is the emf induced in the second coil?

An inductor with inductance L and an inductor with inductance 2L are 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:

The units of motional emf are:

1 weber is the same as:

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:

Suppose this page is perpendicular to a uniform magnetic field and the magnetic flux through it is 5.0 Wb. If the page is turned by 30 $\degree$ around an edge the flux through it will be:

The circuit shown is in a uniform magnetic field that is into the page. The current in the circuit is 0.20 A. At what rate is the magnitude of the magnetic field changing? Is it increasing or decreasing?

A rectangular loop of wire is placed perpendicular to a uniform magnetic field and then spun around one of its sides at frequency f. The induced emf is a maximum when:

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

An electric field is associated with every:

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 current i is given by:

A car travels northward at 75 km/h along a straight road in a region where Earth's magnetic field has a vertical component of 0.50 * 10^-4 T. The emf induced between the left and right side, separated by 1.7 m, is:

A 0.20-cm radius cylinder, 3.0 cm long, is wrapped with wire to form an inductor. At the instant the magnetic field in the interior is 5.0 mT, the energy stored in the field is:

Coils P and Q each have a large number of turns of insulated wire. When switch S is closed, the pointer of galvanometer G is deflected toward the left. Now that S is closed, to make the pointer of G deflect toward the right one could: