Physics Quiz 4

As shown in the figure, a wire and a 10 Ω resistor are used to form a circuit…

75mA, from b to a

A coil lies flat on a tabletop in a region where the magnetic field vector points straight up. The magnetic field vanishes suddenly. When viewed from above, what is the sense of the induced current in this coil as the field fades?

The induced current flows counterclockwise

The magnetic flux through a coil changes steadily from 4.0 × 10⁻⁵ T•m² to 5.0 × 10⁻⁵ T • m in 0.10s. What emf is induced in this coil? 

1.0 × 10⁻⁴ V

A coil of wire containing N turns is in an external magnetic field that is perpendicular to the plane of the coil and it steadily changing. Under these circumstances, an emf ε is induced in the coil. If the rate of change of the magnetic field and the number of turns in the coil are now doubled (but nothing else changes), what will be the induced emf in the coil?

4ε

A bar magnet is pushed through a coil of wire of cross-sectional area 0.020 m² as shown in the figure. The coil has seven turns, and the rate of change of the strength of the magnetic field in it due to the motion of the bar magnet is 0.040 T/s. What is the magnitude of the induced emf in that coil of wire?

5.6 × 10⁻² V

A rectangular loop of wire that can rotate about an axis through its center is placed between the poles of a magnet in a magnetic field with a strength of 0.40 T as shown in the figure. The length of the loop L is 0.16 m and its width w is 0.040 m. What is the magnetic flux through the loop when the plane of the loop makes an angle of 60* with the magnetic field?

2.2 × 10⁻³ T•m²

Two solenoids are close to each other, as shown in the figure, with the switch S open. When the switch is suddenly closed, which way will the induced current flow through the galvanometer in the left-hand solenoid?

from right to left

A flat circular loop of radius 0.10 m is rotating in a uniform magnetic field of 0.20 T. Find the magnetic flux through the loop when the plane of the loop and the magnetic field vector are parallel.

0 T•m²

A bar magnet is oriented above a copper ring, as shown in the figure. The magnet is dropped and passes completely through the ring. As viewed from above, what is the direction of the current induced in the ring after the magnet has completely passed through the ring and is somewhat below it?

clockwise

An outer metal ring surrounds an inner metal ring, as shown in the figure. The current in the outer ring is counterclockwise and decreasing. What is the direction of the induced current in the inner ring?

counterclockwise