Question 1

The magnitude of the magnetic field due to the presence of a charged body

Accepted Answer

A)  varies directly with the speed of the body. 
B)  varies directly with the charge carried by the body. 
C)  varies inversely with the square of the distance between the charged body and the field point. 
D)  depends on the magnetic properties of the space between the charged body and the field point. 
E)  is described by all of these.

Question 2

At a certain instant of time a particle with charge q = 15 $\mu$C is located at x = 2.0 m, y = 5.0 m; its velocity at that time is v = 40 m/s  . If you are at the origin, what do you measure as the magnitude of the magnetic field due to this moving point charge?

Accepted Answer

A)  1.9 pT 
B)  3.8 pT 
C)  2.7 pT 
D)  4.1 pT 
E)  5.9 pT

Question 3

A wire of radius 0.35 cm carries a current of 75 A that is uniformly distributed over its cross-sectional area. The magnetic field  0.20 cm from the center of the wire is approximately

Accepted Answer

A)  2.5 mT 
B)  8.8 $\mu$T 
C)  3.8 mT 
D)  15 mT 
E)  2.9 $\mu$T

Question 4

A circular loop of wire 10 cm in radius carries a current of 20 A. The axial magnetic field 15 cm from the center of the loop is approximately

Accepted Answer

A)  37 $\mu$T 
B)  13$\mu$T 
C)  21$\mu$T 
D)  41$\mu$T 
E)  18 $\mu$T

Question 5

Use the following to answer the next question: 
-A coil of radius R = 5 cm lies inside a long solenoid which carries a current I1 = 10 A and has 800 turns/m. The coil carries a current I2 = 4 A and the normal of the plane of the coil is at an angle $\theta$ = 30$\degree$with the axis of the solenoid. The magnitude of the torque on the coil is

Accepted Answer

A)  1.56 * 10-4 N . m 
B)  2.74 * 10-4 N . m 
C)  5.03 * 10-5 N . m 
D)  3.16 * 10-4 N . m 
E)  none of the above

Question 6

The orbital magnetic moment of an atomic electron is

Accepted Answer

A)  directly proportional to its angular momentum. 
B)  directly proportional to the electronic charge. 
C)  inversely proportional to the mass of the electron. 
D)  quantized as a consequence of the quantization of angular momentum. 
E)  described by all of the above.

Question 7

Point P1 on the hysteresis curve corresponds to

Accepted Answer

A)  approximate saturation. 
B)  the alignment of nearly all atomic magnetic moments. 
C)  maximum applied magnetic field. 
D)  the alignment of virtually all the magnetic domains. 
E)  All of these are correct.

Question 8

If the magnetic field at the center of a square current loop of side L = 40 cm is
2)4 *10-6 T calculate the current flowing around the loop.

Accepted Answer

A)  11 A 
B)  3.4 A 
C)  0.85 A 
D)  0.21 A 
E)  1.7 A

Question 9

Nickel has a density of 8.70 g/cm3 and a molecular mass of 58.7 g/mol. Its magnetic moment is 0.587 Bohr magnetons (1 Bohr magneton = 9.27 *10-24 A · m2). What is its saturation magnetization?

Accepted Answer

A)  4.85* 109 A/m 
B)  8.92* 105 A/m 
C)  9.27 * 10-24 A/m 
D)  8.92 * 1028 A/m 
E)  4.85 * 105 A/m

Question 10

A toroid has 200 turns of wire with a current of 3 A passing through the wire. The inner radius of the toroid is 3 cm and the outer radius is 5 cm. Calculate the magnetic field strength at a radius of 2 cm.

Accepted Answer

A)  6.0 * 10-3 T 
B)  3.0 * 10-3 T 
C)  1.2* 10-2 T 
D)  4.8 F*10-4 T 
E)  none of the above

Question 11

Two wires lying in the plane of this page carry equal currents in opposite directions, as shown. At a point midway between the wires, the magnetic field is

Accepted Answer

A)  zero. 
B)  into the page. 
C)  out of the page. 
D)  toward the top or bottom of the page. 
E)  toward one of the two wires.

Question 12

The graph that best represents B as a function of r for a wire of radius R carrying a current I uniformly distributed over its cross-sectional area is

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 13

When a sample of liquid is inserted into a solenoid carrying a constant current, the magnetic field inside the solenoid decreases by 0.005%. What is the magnetic susceptibility of the liquid?

Accepted Answer

A)  -5 * 10-5  
B)  +5*10-5  
C)  3.6*10-5  
D)  -3.6 * 10-5  
E)  More information is needed to answer this question.

Question 14

Use the following figure to answer the next problem: 
-The tightly wound toroid shown consists of 100 turns of wire, each carrying a current
I = 3 A. If a = 12 cm and b = 15 cm, the magnetic field at r = 18 cm, due to the current in this toroid, is (µ0 = 4 $\pi$ *10-7 N/A2)

Accepted Answer

A)  333 µT 
B)  400 µT 
C)  500 µT 
D)  600 
E)  zero

Question 15

Diamagnetic materials

Accepted Answer

A)  have small negative values of magnetic susceptibility. 
B)  are those in which the magnetic moments of all electrons in each atom cancel. 
C)  experience a small induced magnetic moment when placed in an external magnetic field. 
D)  exhibit the property of diamagnetism independently of temperature. 
E)  are described by all of the above.

Question 16

Each of the figures shown is the source of a magnetic field. In which figure does the magnetic dipole vector (  ) point in the direction of the negative x axis?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 17

A cylindrical bar magnet of radius 0.650 cm and length 8.30 cm has a magnetic dipole moment of magnitude m = 1.40 A · m2. What is the magnetic field at the center of the magnet?

Accepted Answer

A)  125 mT 
B)  23.0 mT 
C)  57.0 mT 
D)  160 mT 
E)  80.0 mT

Question 18

Some substances, when placed in a magnetic field in free space, reduce the magnitude of the magnetic induction in the space they occupy. These substances are

Accepted Answer

A)  ferromagnetic 
B)  not magnetic 
C)  ultramagnetic 
D)  paramagnetic 
E)  diamagnetic

Question 19

In a simple picture of the hydrogen atom, the electron moves in circular orbits around the central proton attracted by the Coulomb force. The lowest (n = 1) energy orbit that is allowed for the electron is at a radius of 5.29 *10-11 m and the second (n = 2) lowest allowed orbit is at 4 times this radius. How many times stronger is the magnetic field strength at the proton due to the orbital motion of the electron in the n = 1 state than the n = 2 state?

Accepted Answer

A)  64 
B)  16 
C)  4 
D)  1 
E)  32

Question 20

The two wires in a DC adapter cable are 5 mm apart and carry a current of 4 A. If the cable is 1.5 m long, calculate the force between the wires and state if this force is attractive or not.

Accepted Answer

A)  9.6 *10-4 N, attractive 
B)  9.6 * 10-7 N, attractive 
C)  1.1 * 10-8 N, attractive 
D)  9.6 *10-4 N, repulsive 
E)  1.1 *10-8 N, repulsive

Exam 7: Sources of the Magnetic Field

The magnitude of the magnetic field due to the presence of a charged body

A circular loop of wire 10 cm in radius carries a current of 20 A. The axial magnetic field 15 cm from the center of the loop is approximately

The orbital magnetic moment of an atomic electron is

Point P₁ on the hysteresis curve corresponds to

If the magnetic field at the center of a square current loop of side L = 40 cm is 2) 4 *10^-⁶ T calculate the current flowing around the loop.

Nickel has a density of 8.70 g/cm³ and a molecular mass of 58.7 g/mol. Its magnetic moment is 0.587 Bohr magnetons (1 Bohr magneton = 9.27 *10^-24 A · m²) . What is its saturation magnetization?

A toroid has 200 turns of wire with a current of 3 A passing through the wire. The inner radius of the toroid is 3 cm and the outer radius is 5 cm. Calculate the magnetic field strength at a radius of 2 cm.

Two wires lying in the plane of this page carry equal currents in opposite directions, as shown. At a point midway between the wires, the magnetic field is

The graph that best represents B as a function of r for a wire of radius R carrying a current I uniformly distributed over its cross-sectional area is

When a sample of liquid is inserted into a solenoid carrying a constant current, the magnetic field inside the solenoid decreases by 0.005%. What is the magnetic susceptibility of the liquid?

Diamagnetic materials

Each of the figures shown is the source of a magnetic field. In which figure does the magnetic dipole vector ( ) point in the direction of the negative x axis?

A cylindrical bar magnet of radius 0.650 cm and length 8.30 cm has a magnetic dipole moment of magnitude m = 1.40 A · m². What is the magnetic field at the center of the magnet?

Some substances, when placed in a magnetic field in free space, reduce the magnitude of the magnetic induction in the space they occupy. These substances are

The two wires in a DC adapter cable are 5 mm apart and carry a current of 4 A. If the cable is 1.5 m long, calculate the force between the wires and state if this force is attractive or not.

Exam 7: Sources of the Magnetic Field

The magnitude of the magnetic field due to the presence of a charged body

At a certain instant of time a particle with charge q = 15 μ\muμ C is located at x = 2.0 m, y = 5.0 m; its velocity at that time is v = 40 m/s . If you are at the origin, what do you measure as the magnitude of the magnetic field due to this moving point charge?

A wire of radius 0.35 cm carries a current of 75 A that is uniformly distributed over its cross-sectional area. The magnetic field 0.20 cm from the center of the wire is approximately

A circular loop of wire 10 cm in radius carries a current of 20 A. The axial magnetic field 15 cm from the center of the loop is approximately

The orbital magnetic moment of an atomic electron is

Point P1 on the hysteresis curve corresponds to

If the magnetic field at the center of a square current loop of side L = 40 cm is 2) 4 *10-6 T calculate the current flowing around the loop.

Nickel has a density of 8.70 g/cm3 and a molecular mass of 58.7 g/mol. Its magnetic moment is 0.587 Bohr magnetons (1 Bohr magneton = 9.27 *10-24 A · m2) . What is its saturation magnetization?

A toroid has 200 turns of wire with a current of 3 A passing through the wire. The inner radius of the toroid is 3 cm and the outer radius is 5 cm. Calculate the magnetic field strength at a radius of 2 cm.

Two wires lying in the plane of this page carry equal currents in opposite directions, as shown. At a point midway between the wires, the magnetic field is

The graph that best represents B as a function of r for a wire of radius R carrying a current I uniformly distributed over its cross-sectional area is

When a sample of liquid is inserted into a solenoid carrying a constant current, the magnetic field inside the solenoid decreases by 0.005%. What is the magnetic susceptibility of the liquid?

Use the following figure to answer the next problem: -The tightly wound toroid shown consists of 100 turns of wire, each carrying a current I = 3 A. If a = 12 cm and b = 15 cm, the magnetic field at r = 18 cm, due to the current in this toroid, is (µ0 = 4 π\piπ *10-7 N/A2)

Diamagnetic materials

Each of the figures shown is the source of a magnetic field. In which figure does the magnetic dipole vector ( ) point in the direction of the negative x axis?

A cylindrical bar magnet of radius 0.650 cm and length 8.30 cm has a magnetic dipole moment of magnitude m = 1.40 A · m2. What is the magnetic field at the center of the magnet?

Some substances, when placed in a magnetic field in free space, reduce the magnitude of the magnetic induction in the space they occupy. These substances are

The two wires in a DC adapter cable are 5 mm apart and carry a current of 4 A. If the cable is 1.5 m long, calculate the force between the wires and state if this force is attractive or not.

Point P₁ on the hysteresis curve corresponds to

If the magnetic field at the center of a square current loop of side L = 40 cm is 2) 4 *10^-⁶ T calculate the current flowing around the loop.

Nickel has a density of 8.70 g/cm³ and a molecular mass of 58.7 g/mol. Its magnetic moment is 0.587 Bohr magnetons (1 Bohr magneton = 9.27 *10^-24 A · m²) . What is its saturation magnetization?

A cylindrical bar magnet of radius 0.650 cm and length 8.30 cm has a magnetic dipole moment of magnitude m = 1.40 A · m². What is the magnetic field at the center of the magnet?