Exam 20: Electromagnetic Induction

A metal rod of length 2.0 m is moved at 6.0 m/s in a direction perpendicular to its length. A 5.0 mT magnetic field is perpendicular to both the rod and its velocity. If the resistance of the rod is 15 mΩ, what is the current in the rod?

A coil is rotated in a magnetic field about an axis perpendicular to both the field and the coil axis (normal to the coil area). During each rotation, how many times does the flux through the coil equal zero?

A coiled loop of wire is in the field region between the poles of an electromagnet, with the axis of the coil aligned with the magnetic field. Which of the following things would NOT result in an induced EMF in the coil?

A 20 turn coil of area 10 cm² is placed in a magnetic field so that the normal to the coil's area is in the same direction as the field. If the magnitude of the field increases from 0.25 T to 0.35 T in 2.0 s, what is the average emf induced in the coil?

An LR circuit is prepared for an experiment, initially with its switch open. The time constant is that time after switch closure at which the current reaches approximately what percentage of its final value?

What is the magnetic energy stored by a 300 mH inductor with a 2.0 A current going through it?

A series LR circuit includes a 9.0 V battery, a resistance of 0.50 Ω, and an inductance of 0.80 H. What is the energy stored by the inductor 2.0 s after the switch is closed?

The induced emf in a straight segment of wire that moves through a region with a magnetic field depends on all of the following, except

A generator is designed to produce a maximum emf of 170 V while rotating at 3200 rpm. The 1531 coils of the generator are circular with diameter 7.5 cm. What is the necessary magnetic field for the generator?

A horizontal desk surface measures 1.3 m by 1.0 m. If the Earth's magnetic field has a magnitude of 0.44 mT and is directed 65° below the horizontal, what is the magnetic flux through the desk surface?

After the switch is closed in a series LR circuit, what is the current when a time equal to four time constants has elapsed?

A metal rod of length 2.0 m is moved at 6.0 m/s in a direction perpendicular to its length. A 5.0 mT magnetic field is perpendicular to both the rod and its velocity. What is the magnetic flux swept through per second by the rod?

The SI unit H (the henry) is equal to a

A 33 mH inductor has a current going through it that is increasing at a rate of 2.3 A/s. What is the magnitude of the induced emf in this coil?

The north end of a bar magnet is pushed downward toward a wire loop in the plane of the paper. In which direction is the induced current, and which way is the induced magnetic field?

A solenoid of length 2.8 cm and diameter 0.75 cm is wound with 160 turns per cm. When the current through the solenoid is 0.20 A, what is the magnetic flux through one of the windings of the solenoid?

A 1.7 H inductor has a current of 6.6 A flowing through it. The current reduces to 3.3 A over a period of 1.6 s. What is the average power the inductor supplies to the circuit as the current reduces?

A transformer has 200 turns on its primary and 12 turns on its secondary. If the input voltage is 2000 V, what is the output voltage?

A series LR circuit includes a 9.0 V battery, a resistance of 0.20 Ω, and an inductor. When the switch is closed, the circuit exhibits a time constant of 200 ms. What is the inductance of the circuit?

A metal rod of length 2.0 m is moved at 6.0 m/s in a direction perpendicular to its length. A 5.0 mT magnetic field is perpendicular to both the rod and its velocity. What is the magnitude of the electric field in the rod?