Question 1

A small cylinder made of a diamagnetic material is brought near a bar magnet. One end of the cylinder is brought near the North pole of the magnet and is repelled. What happens when the other end of the cylinder is brought near the North pole of the magnet?

Accepted Answer

Diamagnetic materials are repelled by magnetic fields. Since one end of the cylinder is repelled by the North pole, the other end will also be repelled.

Question 2

At what distance from a long straight wire carrying a current of 5.0 A is the magnitude of the magnetic field due to the wire equal to the strength of the Earth's magnetic field of about 5.0 × 10^-⁵ T?

Accepted Answer

The magnetic field due to a long straight wire is given by B = (μ₀I)/(2πr). Setting this equal to 5.0 × 10⁻⁵ T and solving for r with I = 5.0 A gives r ≈ 2.0 cm.

Question 3

Two long parallel wires carry currents of 20 A and 5.0 A in opposite directions. The wires are separated by 0.20 m. What is the magnetic field midway between the two wires?

Accepted Answer

The answer of Two long parallel wires carry currents of...

Question 4

In ferromagnetic materials the small regions that act like tiny magnets are called

Accepted Answer

Domains are small regions within a ferromagnetic material that act like tiny magnets.

Question 5

A solenoid with an air core has a magnetic field pointing along its axis in the positive x direction. This solenoid is then filled with a diamagnetic material. What changes will this make to the magnetic field along the axis of the solenoid?

Accepted Answer

A diamagnetic material will slightly reduce the magnetic field inside the solenoid, so the field will point in the same direction but with a smaller magnitude.

Question 6

Two long parallel wires carry currents of 10 A in opposite directions. They are separated by 40 cm. What is the magnetic field in the plane of the wires at a point that is 20 cm from one wire and 60 cm from the other?

Accepted Answer

The answer of Two long parallel wires carry currents of...

Question 7

The magnetic permeability of a ferromagnetic material is

Accepted Answer

Ferromagnetic materials have a magnetic permeability that is much greater than μ_O due to their ability to become strongly magnetized.

Question 8

The magnetic field at a distance of 2 cm from a current carrying wire is 4 μT. What is the magnetic field at a distance of 4 cm from the wire?

Accepted Answer

The magnetic field around a current carrying wire is directly proportional to the inverse of the distance from the wire. This means that if the distance is doubled (from 2 cm to 4 cm), the magnetic field strength would be halved. So, the magnetic field at a distance of 4 cm would be 2 μT.

Question 9

A piece of soft iron is placed in a solenoid increasing the magnetic field in an arrangement that can be switched on and off. Such a device is called

Accepted Answer

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current, and it can be switched on and off. Placing a piece of soft iron inside a solenoid enhances the magnetic field, making it an electromagnet.

Question 10

FIGURE 28-5 
-A long straight wire carrying a 4-A current is placed along the x-axis as shown in Fig. 28-5.
(a) What is the magnitude of the magnetic field at a point P, located at y = 0.02 m, due to the current in this wire?
(b) What is the direction of the magnetic field at a point P, located at y = 0.02 m, due to this wire?

Accepted Answer

The answer of FIGURE 28-5 
-A long straight wire carrying...

Question 11

A long wire carrying a 2.0-A current is placed along the y axis. What is the magnitude of the magnetic field at a point 0.60 m along the x-axis?

Accepted Answer

The answer of A long wire carrying a 2.0-A current...

Question 12

The magnetic field due to the current in a long, straight wire is 8.0 μT at a distance of 4.0 cm from the center of the wire. What is the current in the wire?

Accepted Answer

The magnetic field due to the current in the wire is given by the formula:

B = (μ0 * I) / (2π * r)

where B is the magnetic field, I is the current, r is the distance from the center of the wire, and μ0 is the permeability of free space.

We are given that B = 8.0 μT and r = 4.0 cm = 0.04 m. We can rearrange the formula to solve for I:

I = (2π * r * B) / μ0

Substituting the given values, we get:

I = (2π * 0.04 m * 8.0 * 10^-6 T) / (4π * 10^-7 Tm/A)

Solving this gives:

I = 1.6 A

Therefore, the current in the wire is 1.6 A, which is option E.

Question 13

How do paramagnetic materials differ from diamagnetic materials?

Accepted Answer

Paramagnetic materials have unpaired electrons that create a permanent magnetic dipole moment, whereas diamagnetic materials do not have unpaired electrons and do not have a permanent dipole moment.

Question 14

The magnetic field due to a 2-A current flowing in a long, straight wire is 8 μT at a point P, a certain distance away from the wire. How far is this point from the center of the wire?

Accepted Answer

The answer of The magnetic field due to a 2-A...

Question 15

The magnitude of the magnetic field 8.0 cm from a straight wire carrying a current of 6.0 A is

Accepted Answer

The answer of The magnitude of the magnetic field 8.0...

Question 16

Ferromagnetic materials lose their ability to form permanent magnets if

Accepted Answer

Ferromagnetic materials lose their permanent magnetism when heated above their Curie temperature because the thermal energy disrupts the alignment of magnetic domains.

Question 17

A high power line carrying 1000 A generates what magnetic field at the ground, 10 m away?

Accepted Answer

The answer of A high power line carrying 1000 A...

Question 18

The coulomb is the same as

Accepted Answer

The answer of The coulomb is the same as
...

Question 19

Which of the solenoids described below has the greatest magnetic field along its axis?

Accepted Answer

The magnetic field inside a solenoid is given by B = μ₀ * (N/L) * I. Solenoid E has the highest number of turns per unit length (2N/2L = N/L) and the highest current (2I), resulting in the greatest magnetic field.

Question 20

In using Ampere's law, the integral must be evaluated

Accepted Answer

Ampere's law states that the integral of the magnetic field around a closed path is proportional to the current enclosed within that path. Therefore, the integral must be evaluated around a closed path.

Quiz 28: Sources of Magnetic Field