Question 1

When a ferromagnetic material that has been magnetized is brought to a temperature greater than the Curie temperature, what happens to its residual magnetism.

Accepted Answer

When a ferromagnetic material is brought to a temperature greater than its Curie temperature, the thermal energy causes the magnetic domains to become disordered and lose their alignment resulting in the disappearance of residual magnetization.

Question 2

The planetary model of the hydrogen atom consists of an electron in a circular orbit about a proton. The motion of the electron of charge 1.60 × 10−¹⁹ C creates an electric current. The radius of the electron orbit is 5.30 × 10−¹¹ m and the electron's velocity is 2.20 × 10⁶ m/s. What is the magnetic field strength at the location of the proton?

Accepted Answer

The answer of The planetary model of the hydrogen atom...

Question 3

We find that 2N current loops are coplanar and coaxial. The first has radius a and current I. The second has radius 2a and current 2I, and the pattern is repeated up to the Nth, which has radius Na and current NI. The current in the loops alternates in direction from loop to loop as seen from above. Thus the current in the first loop is counterclockwise, in the next clockwise, up to the last loop where it is again clockwise. The magnitude of the magnetic field at the center of the loops is

Accepted Answer

The answer of We find that 2N current loops are...

Question 4

A superconducting wire carries a current of 1.0 × 10⁴ A. Find the magnetic field at a distance of 1.0 m from the wire.

Accepted Answer

The answer of A superconducting wire carries a current of...

Question 5

An ideal solenoid of radius a has n turns per unit length and current I. The magnetic flux Φ_B through any circular area of radius a inside the solenoid, centered on and perpendicular to the solenoid axis is

Accepted Answer

The magnetic field inside the ideal solenoid is constant and given by μnI, where μ is the permeability of the medium inside the solenoid. Thus, the magnetic flux through any circular area of radius a inside the solenoid is given by Φ = Bπa^2, where B=μnI. Substituting this value of B in Φ, we get Φ = Bπa^2 = (μnI)πa^2. This gives us the option C as the correct choice.

Question 6

What current in a solenoid 15.0-cm long wound with 100 turns would produce a magnetic field equal to that of the Earth, 5.00 × 10−⁵ T?

Accepted Answer

The answer of What current in a solenoid 15.0-cm long...

Question 7

Which of the following type(s) of materials is(are) repelled when a magnet is brought near by?

Accepted Answer

Diamagnetic materials are repelled by a magnet.

Question 8

Two current loops are coaxial and coplanar. One has radius a and the other has radius 2a. Current 2I in the outer loop is antiparallel to current I in the inner loop. The magnitude of the magnetic field at the center of the two loops is

Accepted Answer

The answer of Two current loops are coaxial and coplanar....

Question 9

An ideal solenoid of radius a has n turns per unit length and current I. The magnetic flux Φ_B through any area completely inside the solenoid, centered on the solenoid axis but at a 45° angle to the axis, so that it touches the inside of the solenoid, as shown below, is

Accepted Answer

The magnetic field inside a solenoid is given by B = μnI, where n is the number of turns per unit length and I is the current. At a point inside the solenoid that is offset from the axis by a distance r, the field is given by B = μnIr/2a. At the surface of the solenoid, r = a, so B = μnI/2. 
The magnetic flux through an area A is given by Φ = BAcosθ, where θ is the angle between the field and the area. In this case, the area is at a 45° angle to the axis, so cosθ = 1/√2. The area is a circle with radius a, so its area is πa^2. Putting it all together, we get Φ = μnaIa^2/2√2. 
Therefore, the correct answer is C.

Question 10

Three coplanar parallel straight wires carry equal currents I as shown below. The current in the outer wires is directed to the right, and that in the middle wire is directed to the left. Each pair of wires is a distance a apart. The direction of the magnetic force on the middle wire

Accepted Answer

The answer of Three coplanar parallel straight wires carry equal...

Question 11

Three coplanar parallel straight wires carry equal currents I to the right as shown below. Each pair of wires is a distance a apart. The direction of the magnetic force on the middle wire

Accepted Answer

The answer of Three coplanar parallel straight wires carry equal...

Question 12

Three coplanar parallel straight wires carry equal currents I to the right as shown below. The current in the upper two wires is directed to the right, but the current in the bottom wire is directed to the left. Each pair of wires is a distance a apart. The direction of the magnetic force on the middle wire

Accepted Answer

The answer of Three coplanar parallel straight wires carry equal...

Question 13

We find that N current loops are coplanar and coaxial. The first has radius a and current I. The second has radius 2a and current 2I, and the pattern is repeated up to the Nth, which has radius Na and current NI. The current in each loop is counterclockwise as seen from above. The magnitude of the magnetic field at the center of the loops is

Accepted Answer

The answer of We find that N current loops are...

Question 14

A long solenoid (n = 80 turns/cm) carries a current of 70 mA. Determine the magnitude of the magnetic field inside the solenoid.

Accepted Answer

The answer of A long solenoid (n = 80 turns/cm)...

Question 15

Two wires, each having a weight per unit length of 1.0 × 10−⁴ N/m, are strung parallel, one 0.10 m above the other. If the wires carry the same current, though in opposite directions, how great must the current in each wire be for the magnetic field of the lower conductor to balance the weight of the upper conductor?

Accepted Answer

The answer of Two wires, each having a weight per...

Quiz 30: Sources of the Magnetic Field

When a ferromagnetic material that has been magnetized is brought to a temperature greater than the Curie temperature, what happens to its residual magnetism.

A superconducting wire carries a current of 1.0 × 104 A. Find the magnetic field at a distance of 1.0 m from the wire.

An ideal solenoid of radius a has n turns per unit length and current I. The magnetic flux ΦB through any circular area of radius a inside the solenoid, centered on and perpendicular to the solenoid axis is

What current in a solenoid 15.0-cm long wound with 100 turns would produce a magnetic field equal to that of the Earth, 5.00 × 10−5 T?

Which of the following type(s) of materials is(are) repelled when a magnet is brought near by?

Two current loops are coaxial and coplanar. One has radius a and the other has radius 2a. Current 2I in the outer loop is antiparallel to current I in the inner loop. The magnitude of the magnetic field at the center of the two loops is

An ideal solenoid of radius a has n turns per unit length and current I. The magnetic flux ΦB through any area completely inside the solenoid, centered on the solenoid axis but at a 45° angle to the axis, so that it touches the inside of the solenoid, as shown below, is

Three coplanar parallel straight wires carry equal currents I as shown below. The current in the outer wires is directed to the right, and that in the middle wire is directed to the left. Each pair of wires is a distance a apart. The direction of the magnetic force on the middle wire

Three coplanar parallel straight wires carry equal currents I to the right as shown below. Each pair of wires is a distance a apart. The direction of the magnetic force on the middle wire

A long solenoid (n = 80 turns/cm) carries a current of 70 mA. Determine the magnitude of the magnetic field inside the solenoid.

A superconducting wire carries a current of 1.0 × 10⁴ A. Find the magnetic field at a distance of 1.0 m from the wire.

An ideal solenoid of radius a has n turns per unit length and current I. The magnetic flux Φ_B through any circular area of radius a inside the solenoid, centered on and perpendicular to the solenoid axis is

What current in a solenoid 15.0-cm long wound with 100 turns would produce a magnetic field equal to that of the Earth, 5.00 × 10−⁵ T?

An ideal solenoid of radius a has n turns per unit length and current I. The magnetic flux Φ_B through any area completely inside the solenoid, centered on the solenoid axis but at a 45° angle to the axis, so that it touches the inside of the solenoid, as shown below, is