Exam 31: Electromagnetic Induction

Five series RL circuits are identical except for the values of their inductance. They are all connected to the same emf V. After the switch was open in all circuits for a long time, the switch is closed at $t = 0$ s. The graph that most likely shows the current in the circuit with the larger inductance value is

A region in space is subject to a 100-G magnetic field and a 2.00 *10⁶ N/C electric field. The total energy density in this region is

Energy in stored in a electric field by

An adjustable single loop positioned in the plane of the page is placed in a magnetic field B = 1.5 T, making an angle of 30^o with the page. When the cross-sectional area of the loop is reduced from 0.50 m² to 0.35 m² in 0.30 s, the average emf induced in the coil is

A series RL circuit with inductance L and resistance R is connected to an emf V. A second series circuit connected to the same emf V is identical except that its resistance is 4R. The ratio of the time constant of the first circuit to the time constant of the second circuit is

A series RL circuit with inductance L and resistance R is connected to an emf V. After a time the current reaches a final value of 6.0 A. A second series circuit connected to the same emf V is identical except that its inductance is 4L. The ratio of the rate of change of current in the first circuit to that in the second circuit is

When the number of loops of wire in a coil is doubled, assuming all the other factors stay constant, the induced emf

A long solenoid is surrounded by a circular coil. If the current changes in the solenoid, the emf induced in the coil as measured between the terminals of the coil is directly proportional to all of the following except

A 6.0-mH coil carries a current of 3.0 A. The energy stored in the coil's magnetic field is

A series RL circuit with inductance 6.0 mH and resistance 20 $\Omega$ is connected to a 12.0-V battery of negligible internal resistance. The current in the circuit 4.0 $\mu$ s after the switch is closed is

A circular loop of wire is rotated at constant angular speed about its symmetry axis, whose direction can be varied, in a uniform magnetic field pointing vertically upward. To get no induced emf, the loop's axis of rotation should

A conducting bar is slid at constant velocity toward the positive x direction, along two conducting rods connected across a resistor R, as shown in the figure here. The graph that most likely shows the current generated by the apparatus is

A long solenoid is surrounded by a circular coil. The solenoid is replaced with an ideal toroid that produces the same average magnetic field in its interior as was present in the solenoid (and no magnetic field outside its enclosed region). The emf induced in the coil if the current in the toroid changes at the same rate is

A solid conducting cube is placed on your page near the left side and oriented square with the page. When the cube is moved toward the right side of the page, in a uniform magnetic field pointing out of the page, an emf develops between the two surfaces

A rod lies in the plane of the page and moves at constant velocity, perpendicular to the rod, toward the top of the page, through a magnetic field that points out of the page. The correct statement concerning the potential induced across the rod is

A conducting square loop is placed around a bar magnet. As the loop moves away from the magnet,

Five series RL circuits are identical except for the values of their resistance. They are all connected to the same emf V. After the switch was open in all circuits for a long time, the switch is closed at $t = 0$ s. The graph that most likely shows the current in the circuit with the larger resistance value is

A simple RL circuit contains a 4.0- $\Omega$ resistor and an 32-H inductor. The circuit's time constant is

A series RL circuit with inductance L, resistance R, and a switch is connected to an emf V. The switch is closed at $t = 0$ s. The graph that most likely shows the change in current in the circuit as a function of time is

A series RL circuit with inductance L, resistance R, and a switch is connected to an emf V. The current in the circuit is zero when the switch is closed at $t = 0$ s. The current increases to 70% of its final value in 4.0 s. The time constant of the circuit is