Question 1

A 200-loop coil of cross sectional area 8.5 cm² lies in the plane of the paper. Directed out of the plane of the paper is a magnetic field of 0.06 T. The field out of the paper decreases to 0.02 T in 12 milliseconds. What is the direction of the current induced?

Accepted Answer

The magnetic field is decreasing, so the induced current will act to oppose this decrease. According to Lenz's Law, the induced current will be in a direction that tries to maintain the original magnetic field direction, which is out of the paper. Therefore, the induced current will be counterclockwise.

Question 2

A circular loop of wire is in the plane of the paper. The south pole of a bar magnet is being moved from a position in front of the paper in a direction away from the center of the loop. The direction of the induced current in the loop

Accepted Answer

The answer of A circular loop of wire is in...

Question 3

A circular coil of copper wire is lying flat on a horizontal table. A bar magnet is held with its south pole downward, vertically above the center of the coil. The magnet is released from rest and falls toward the coil. As viewed from above, you can say that, as it falls, the magnet induces

Accepted Answer

As the magnet falls towards the coil, the changing magnetic field induces an electric current in the coil according to Faraday's law of electromagnetic induction. This current will create its own magnetic field that will interact with the falling magnet. According to Lenz's law, the induced magnetic field will be in a direction that opposes the motion of the falling magnet. Therefore, the induced current in the coil will flow in a direction that creates a magnetic field that opposes the south pole of the magnet. This can only be achieved by a clockwise current in the loop, looking from above.

Question 4

A coil lies flat on a horizontal table top in a region where the magnetic field points straight down. The magnetic field disappears suddenly. When viewed from above, what is the direction of the induced current in this coil as the field disappears?

Accepted Answer

The answer of A coil lies flat on a horizontal...

Question 5

A coil lies flat on a table top 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?

Accepted Answer

According to Lenz's Law, the induced current will flow in a direction that opposes the change in magnetic flux. Since the magnetic field is pointing up and vanishes, the induced current will create its own magnetic field pointing up to oppose the decrease. When viewed from above, this results in a counterclockwise current.

Question 6

According to Lenz's law, the direction of an induced current in a conductor will be that which tends to produce which of the following effects?

Accepted Answer

Lenz's law states that the direction of an induced current is such that it opposes the change in magnetic flux that produced it, thereby opposing the effect which produces it.

Question 7

FIGURE 29-2 
-The wire in Fig. 29-2 carries a current I that is decreasing with time at a constant rate. The induced emf in each of the loops is such that

Accepted Answer

The answer of FIGURE 29-2 
-The wire in Fig. 29-2...

Question 8

A rectangular coil lies flat on a horizontal surface. A bar magnet is held above the center of the coil with its north pole pointing down. What is the direction of the induced current in the coil?

Accepted Answer

The answer of A rectangular coil lies flat on a...

Question 9

A coil lies flat on a level table top in a region where the magnetic field vector points straight up. The magnetic field suddenly grows stronger. When viewed from above, what is the direction of the induced current in this coil as the field increases?

Accepted Answer

The answer of A coil lies flat on a level...

Question 10

FIGURE 29-1 
-The three loops of wire shown in Fig. 29-1 are all subject to the same uniform magnetic field  that does not vary with time. Loop 1 oscillates back and forth as the bob in a pendulum, loop 2 rotates about a vertical axis, and loop 3 oscillates up and down at the end of a spring. Which loop, or loops, will have an induced emf?

Accepted Answer

The answer of FIGURE 29-1 
-The three loops of wire...

Question 11

As a coil is removed from a magnetic field an emf is induced in the coil causing a current to flow within the coil. This current interacts with the magnetic field producing a force which

Accepted Answer

According to Lenz's Law, the induced current will create a magnetic field that opposes the change in the original magnetic field, resulting in a force that acts opposite to the coil's motion.

Question 12

A circular loop of wire of area 25 cm² lies in the plane of the paper. An increasing magnetic field B is coming out of the paper. What is the direction of the induced current in the loop?

Accepted Answer

The answer of A circular loop of wire of area...

Question 13

A circular loop of wire is in the plane of the paper. The north pole of a bar magnet is being moved toward the center of the loop from a position in front of the paper. The direction of the induced current in the loop

Accepted Answer

According to Lenz's Law, the induced current will flow in a direction that opposes the change in magnetic flux. As the north pole of the magnet approaches, the magnetic flux through the loop increases, and the induced current will be counterclockwise to create a magnetic field opposing the approaching north pole.

Question 14

A circular coil of copper wire is lying flat on a horizontal table. A bar magnet is held with its south pole downward, vertically above the center of the coil. The magnet is kept stationary with respect to the coil. As viewed from above, you can say that the magnet induces

Accepted Answer

The answer of A circular coil of copper wire is...

Question 15

A circular loop of wire of area 25 cm² lies in the plane of the paper. An decreasing magnetic field B is coming out of the paper. What is the direction of the induced current in the loop?

Accepted Answer

According to Lenz's Law, the induced current will flow in a direction that opposes the change in magnetic flux. Since the magnetic field is decreasing and coming out of the paper, the induced current will be counterclockwise to try to maintain the magnetic field coming out of the paper.

Question 16

Magnetic flux depends upon

Accepted Answer

Magnetic flux depends on the magnetic field, the orientation of the area with respect to the field, and the area involved.

Question 17

A long straight wire lies on a horizontal table and carries an ever-increasing current northward. Two coils of wire lie flat on the table, one on either side of the wire. When viewed from above, the induced current circles

Accepted Answer

The answer of A long straight wire lies on a...

Question 18

For the maximum induced emf in the coil of a generator, the term sin ωt has a value of one.

Accepted Answer

The maximum induced emf in a coil of a generator occurs when the rate of change of magnetic flux linkage is at its maximum, which happens when the term sin ωt (representing the alternating current) has a value of one.

Question 19

A rectangular coil lies flat on a horizontal surface. A bar magnet is held above the center of the coil with its north pole pointing down. If the magnet is dropped from this position what is the direction of the induced current in the coil?

Accepted Answer