Question 1

A wire lying in the plane of the page carries a current toward the bottom of the page,as shown in the figure.What is the direction of the magnetic force it produces on an electron that is moving to the left directly toward the wire,as shown?

Accepted Answer

The answer of A wire lying in the plane of...

Question 2

A ring with a clockwise current (as viewed from above the ring)is situated with its center directly above another ring,which has a counter-clockwise current,as shown in the figure.In what direction is the net magnetic force exerted on the top ring due to the bottom ring?

Accepted Answer

The answer of A ring with a clockwise current (as...

Question 3

Two long parallel wires placed side-by-side on a horizontal table carry identical size currents in opposite directions.The wire on your right carries current directly toward you,and the wire on your left carries current directly away from you.From your point of view,the magnetic field at a point exactly midway between the two wires

Accepted Answer

The answer of Two long parallel wires placed side-by-side on...

Question 4

A long,straight,horizontal wire carries current toward the east.A proton moves toward the east alongside and just south of the wire.What is the direction of the magnetic force on the proton?

Accepted Answer

The right-hand rule indicates that the magnetic field around the wire circulates clockwise when viewed from the east. Since the proton is moving in the same direction as the current (east) and is located to the south of the wire, the magnetic force on it will be directed toward the north.

Question 5

Two long parallel wires are placed side-by-side on a horizontal table and carry current in the same direction.The current in one wire is 20 A,and the current in the other wire is 5 A.If the magnetic force on the 20-A wire has magnitude F,what is the magnitude of the magnetic force on the 5-A wire? No external magnetic fields are present.

Accepted Answer

According to Newton's third law, the magnetic force exerted by one wire on the other is equal in magnitude and opposite in direction. Therefore, the magnitude of the magnetic force on the 5-A wire is the same as the force on the 20-A wire, which is F.

Question 6

A very long straight current-carrying wire produces a magnetic field of 20 mT at a distance d from the wire.To measure a field of 5 mT due to this wire,you would have to go to a distance from the wire of

Accepted Answer

The magnetic field produced by a current-carrying wire decreases with distance from the wire according to the inverse square law. This means that if you double the distance from the wire, the magnetic field strength will decrease by a factor of four.

Using this relationship and the given information, we can set up the following proportion:

20 mT / d = 5 mT / x

where x is the distance from the wire at which we want to measure a field of 5 mT.

Solving for x, we get:

x = (5 mT * d) / 20 mT = 0.25d

Therefore, to measure a field of 5 mT, we need to be at a distance from the wire of 0.25d.

To convert this to a distance that is a multiple of d, we can divide both sides by d:

x / d = 0.25

x = 0.25d

So, the answer is choice C, 4d. We need to be four times the original distance from the wire to measure a field of 5 mT.

Question 7

A flat circular wire loop lies in a horizontal plane on a table and carries current in a counterclockwise direction when viewed from above.At this point,the earth's magnetic field points to the north and dips below the horizontal.Which side of the coil tends to lift off of the table due to the magnetic torque on the loop?

Accepted Answer

The magnetic field of the Earth is directed downward at an angle below the horizontal. The current loop produces a magnetic field that is perpendicular to the plane of the loop. The interaction between the two magnetic fields produces a torque on the loop that tends to align the loop with the Earth's magnetic field. The side of the loop that is closest to the north pole of the Earth will experience a force upward, while the side of the loop that is closest to the south pole of the Earth will experience a force downward. This will cause the loop to rotate until it is aligned with the Earth's magnetic field, with the south side of the loop facing up.

Question 8

An object is hung using a metal spring.If now a current is passed through the spring,what will happen to this system?

Accepted Answer

When a current is passed through the spring, it heats up due to the resistance of the metal. This causes the metal to expand slightly. However, the dominant effect in this scenario is the electromagnetic force generated by the current flowing through the spring. This force causes the coils of the spring to contract, effectively shortening the spring and raising the weight attached to it.

Question 9

A long,straight,horizontal wire carries current toward the east.An electron moves toward the east alongside and just south of the wire.What is the direction of the magnetic force on the electron?

Accepted Answer

According to the right-hand rule, if an electron moves towards the east alongside a wire carrying current towards the east, the direction of the magnetic force will be towards the south.

Question 10

A long,straight wire carrying a current is placed along the y-axis.If the direction of the current is in the +y direction,what is the direction of the magnetic field due to this wire as you view it in such a way that the current is coming directly toward you?

Accepted Answer

According to the right hand rule, if the current is in the positive y-direction and the observer is looking towards it, then the direction of the magnetic field will be counterclockwise around the wire, which is in the y-z plane. Therefore, the magnetic field will be in the counterclockwise direction around the y-axis.

Question 11

A negatively charged particle -Q is moving to the right,directly above a wire having a current I flowing to the right,as shown in the figure.In what direction is the magnetic force exerted on the particle due to the current?

Accepted Answer

The answer of A negatively charged particle -Q is moving...

Question 12

A wire lying in the plane of this page carries a current directly toward the top of the page.What is the direction of the magnetic force this current produces on an electron that is moving perpendicular to the page and outward from it on the left side of the wire?

Accepted Answer

The answer of A wire lying in the plane of...

Question 13

The maximum torque on a flat current-carrying loop occurs when the angle between the plane of the loop's area and the magnetic field vector is

Accepted Answer

The answer of The maximum torque on a flat current-carrying...

Question 14

Two long parallel wires are placed side-by-side on a horizontal table.If the wires carry current in opposite directions,

Accepted Answer

When two parallel wires carrying current in opposite directions, they experience a force of attraction, which is known as the magnetic force. The magnetic field produced by one wire is perpendicular to the magnetic field produced by the other wire. As a result, the two magnetic fields interact, causing a force of repulsion between the two wires. Therefore, the wires push away from each other.

Question 15

Two long parallel wires are placed side-by-side on a horizontal table.If the wires carry current in the same direction,

Accepted Answer

When two parallel wires carry current in the same direction, they experience a magnetic force that pulls them toward each other due to the interaction of their magnetic fields. This is a consequence of Ampère's force law.

Question 16

Two long,parallel wires carry currents of different magnitudes.If the current in one of the wires is doubled and the current in the other wire is halved,what happens to the magnitude of the magnetic force that each wire exerts on the other?

Accepted Answer

The magnetic force between two parallel wires is given by the expression F = (μ₀I₁I₂L)/(2πr), where I₁ and I₂ are the currents, L is the length of the wires, r is the distance between them, and μ₀ is the magnetic constant. 
If we double the current in one wire (I₁→2I₁) and halve the current in the other wire (I₂→(1/2)I₂), the force expression becomes F' = (μ₀ x 2I₁ x (1/2)I₂ x L)/(2πr) = F. 
Therefore, the magnitude of the magnetic force that each wire exerts on the other stays the same.

Question 17

Which of the following are units for the magnetic moment? (There could be more than one correct choice. )

Accepted Answer

The answer of Which of the following are units for...

Question 18

Two long parallel wires placed side-by-side on a horizontal table carry identical current straight toward you.From your point of view,the magnetic field at a point exactly between the two wires

Accepted Answer

The two wires carrying identical currents in the same direction would create magnetic fields that point in the same direction between the wires and opposite directions outside the wires. At the exact midpoint between the wires, the magnetic fields created by each wire cancel each other out, resulting in a net magnetic field of zero. Therefore, the answer is E - the magnetic field is zero.

Question 19

Two long,parallel wires carry currents of different magnitudes.If the amount of current in one of the wires is doubled,what happens to the magnitude of the force that each wire exerts on the other?

Accepted Answer

The force between two parallel wires is directly proportional to the product of the currents and inversely proportional to the distance between them. When the current in one wire is doubled, the force between the two wires is also doubled. Therefore, the magnitude of the force is increased by a factor of 2.

Question 20

When two long parallel wires carry unequal currents,the magnitude of the magnetic force that one wire exerts on the other is F.If the current in both wires is now doubled,what is the magnitude of the new magnetic force on each wire?

Accepted Answer

The answer of When two long parallel wires carry unequal...

Quiz 22: Magnetism