Question 1

At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

Accepted Answer

A)  zero. 
B)  upward. 
C)  toward the north. 
D)  toward the south. 
E)  downward. 
A)  zero. 
B)  upward. 
C)  toward the north. 
D)  toward the south. 
E)  downward.

Question 2

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 that is 0.60 m from the origin along the x-axis? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  0.67 µT 
B)  1.3 µT 
C)  0.12 µT 
D)  6.7 T 
E)  12 T 
A)  0.67 µT 
B)  1.3 µT 
C)  0.12 µT 
D)  6.7 T 
E)  12 T

Question 3

A doubly charged ion with speed 6.9 × 106 m/s enters a uniform 0.80-T magnetic field, traveling perpendicular to the field. Once in the field, it moves in a circular arc of radius 30 cm. What is the mass of this ion? (e = 1.60 × 10-19 C)

Accepted Answer

A)  11 × 10-27 kg 
B)  6.7 × 10-27 kg 
C)  3.3 × 10-27 kg 
D)  8.2 × 10-27 kg 
A)  11 × 10-27 kg 
B)  6.7 × 10-27 kg 
C)  3.3 × 10-27 kg 
D)  8.2 × 10-27 kg

Question 4

A straight wire is carrying a current of 2.0 A. It is placed at an angle of 60° with respect to a magnetic field of strength 0.20 T. If the wire experiences a force of 0.40 N, what is the length of the wire?

Accepted Answer

A)  1.0 m 
B)  1.2 m 
C)  1.4 m 
D)  1.6 m 
E)  1.8 m 
A)  1.0 m 
B)  1.2 m 
C)  1.4 m 
D)  1.6 m 
E)  1.8 m

Question 5

A straight 1.0-m long wire is carrying a current. The wire is placed perpendicular to a magnetic field of strength 0.20 T. If the wire experiences a force of 0.60 N, what is the current in the wire?

Accepted Answer

A)  2.0 A 
B)  1.0 A 
C)  3.0 A 
D)  4.0 A 
E)  5.0 A 
A)  2.0 A 
B)  1.0 A 
C)  3.0 A 
D)  4.0 A 
E)  5.0 A

Question 6

What is the strength of the magnetic field at the center of a circular loop of wire of diameter 8.0 cm when a current of 2.0 A flows in the wire? 
(μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

Question 7

The magnetic field at point P due to a 2.0-A current flowing in a long, straight, thin wire is 8.0 μT. How far is point P from the wire? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  2.0 cm 
B)  2.5 cm 
C)  4.0 cm 
D)  5.0 cm 
E)  10 cm 
A)  2.0 cm 
B)  2.5 cm 
C)  4.0 cm 
D)  5.0 cm 
E)  10 cm

Question 8

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 Earth's magnetic field of about 5.0 × 10-5 T? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  1.0 mm 
B)  1.0 cm 
C)  2.0 cm 
D)  3.0 cm 
E)  4.0 cm 
A)  1.0 mm 
B)  1.0 cm 
C)  2.0 cm 
D)  3.0 cm 
E)  4.0 cm

Question 9

An ideal solenoid with 400 turns has a radius of 0.040 m and is 40 cm long. If this solenoid carries a current of 12 A, what is the magnitude of the magnetic field at the center of the solenoid? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  16 mT 
B)  4.9 mT 
C)  15 mT 
D)  6.0 mT 
E)  9.0 mT 
A)  16 mT 
B)  4.9 mT 
C)  15 mT 
D)  6.0 mT 
E)  9.0 mT

Question 10

A rigid rectangular loop, measuring 0.30 m by 0.40 m, carries a current of 9.9 A, as shown in the figure. A uniform external magnetic field of magnitude 1.8 T in the -x direction is present. Segment CD is in the xz-plane and forms a 19° angle with the z-axis, as shown. What is the y component of the magnetic force on segment AB of the loop?

Accepted Answer

A)  +5.1 N 
B)  -5.1 N 
C)  +1.7 N 
D)  -1.7 N 
E)  0.0 N 
A)  +5.1 N 
B)  -5.1 N 
C)  +1.7 N 
D)  -1.7 N 
E)  0.0 N

Question 11

At point P the magnetic field due to a long straight wire carrying a current of 2.0 A is 1.2 µT. How far is P from the wire? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  11 cm 
B)  22 cm 
C)  33 cm 
D)  44 cm 
E)  55 cm 
A)  11 cm 
B)  22 cm 
C)  33 cm 
D)  44 cm 
E)  55 cm

Question 12

An ideal solenoid having a coil density of 5000 turns per meter is 10 cm long and carries a current of 4.0 A. What is the strength of the magnetic field at its center?

Accepted Answer

A)  3.1 mT 
B)  6.2 mT 
C)  13 mT 
D)  25 mT 
A)  3.1 mT 
B)  6.2 mT 
C)  13 mT 
D)  25 mT

Question 13

A flat circular loop of wire is in a uniform magnetic field of 0.30 T. The diameter of the loop is 1.0 m, and a 2.0-A current flows in it. What is the magnitude of the magnetic torque on the loop when the plane of the loop is parallel to the magnetic field?

Accepted Answer

A)  0.00 N ∙ m 
B)  0.41 N ∙ m 
C)  0.47 N ∙ m 
D)  0.52 N ∙ m 
A)  0.00 N ∙ m 
B)  0.41 N ∙ m 
C)  0.47 N ∙ m 
D)  0.52 N ∙ m

Question 14

A long straight wire has a constant current flowing to the right. A rectangular metal loop is situated above the wire, and also has a constant current flowing through it, as shown in the figure. Which one of the following statements is true?

Accepted Answer

A)  The net magnetic force on the rectangle is upward, and there is also a nonzero torque on the rectangle. 
B)  The net magnetic force on the rectangle is zero, and the net torque on it is zero. 
C)  The net magnetic force on the rectangle is downward, and there is also a nonzero torque on the rectangle. 
D)  The net magnetic force on the rectangle is zero, but there is a nonzero torque on the rectangle. 
E)  The net magnetic force on the rectangle is downward, and the net torque on it is zero. 
A)  The net magnetic force on the rectangle is upward, and there is also a nonzero torque on the rectangle. 
B)  The net magnetic force on the rectangle is zero, and the net torque on it is zero. 
C)  The net magnetic force on the rectangle is downward, and there is also a nonzero torque on the rectangle. 
D)  The net magnetic force on the rectangle is zero, but there is a nonzero torque on the rectangle. 
E)  The net magnetic force on the rectangle is downward, and the net torque on it is zero.

Question 15

In the figure, a rectangular current loop is carrying current I1 = 7.0 A, in the direction indicated, near a long wire carrying a current Iw. The long wire is parallel to the sides of the rectangle. The rectangle loop has length 0.80 m and its sides are 0.10 m and 0.70 m from the wire. If the net force on the loop is to have magnitude $1.7 \times 10 ^ { - 6 } \mathrm {~N}$ and is to be directed towards the wire, what must be the magnitude and direction (from top to bottom or from bottom to top in the sketch) of the current Iw in the wire? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

0.18 A, fr

Question 16

A proton moving with a velocity of 4.0 × 104 m/s enters a magnetic field of 0.20 T. If the angle between the velocity of the proton and the direction of the magnetic field is 60°, what is the magnitude of the magnetic force on the proton? (e = 1.60 × 10-19C)

Accepted Answer

A)  1.8 × 10-15 N 
B)  0.60 × 10-15 N 
C)  1.1 × 10-15 N 
D)  2.2 × 10-15 N 
E) 3)3 × 10-15 N 
A)  1.8 × 10-15 N 
B)  0.60 × 10-15 N 
C)  1.1 × 10-15 N 
D)  2.2 × 10-15 N 
E) 3)3 × 10-15 N

Question 17

A negatively-charged particle moves across a constant uniform magnetic field that is perpendicular to the velocity of the particle. The magnetic force on this particle

Accepted Answer

A)  causes the particle to speed up. 
B)  causes the particle to slow down. 
C)  causes the particle to accelerate. 
D)  is in the same direction as the particle's velocity. 
E)  is opposite the direction of the particle's velocity. 
A)  causes the particle to speed up. 
B)  causes the particle to slow down. 
C)  causes the particle to accelerate. 
D)  is in the same direction as the particle's velocity. 
E)  is opposite the direction of the particle's velocity.

Question 18

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

A)  points upward. 
B)  points downward. 
C)  points toward you. 
D)  points away from you. 
E)  is zero. 
A)  points upward. 
B)  points downward. 
C)  points toward you. 
D)  points away from you. 
E)  is zero.

Question 19

An electron traveling toward the magnetic north with speed 400 km/s enters a region where the earth's magnetic field has the magnitude 5.0 × 10-5 T and is directed downward at 45° below horizontal. What magnitude magnetic force acts on the electron? (e = 1.60 × 10-19C)

Accepted Answer

Question 20

An ideal solenoid having 200 turns and carrying a current of 2.0 A is 25 cm long. What is the magnitude of the magnetic field at the center of the solenoid? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

Exam 24: Magnetic Fields and Forces

At a particular instant, a proton moves toward the east in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

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 that is 0.60 m from the origin along the x-axis? (μ0 = 4π × 10-7 T ∙ m/A)

A doubly charged ion with speed 6.9 × 106 m/s enters a uniform 0.80-T magnetic field, traveling perpendicular to the field. Once in the field, it moves in a circular arc of radius 30 cm. What is the mass of this ion? (e = 1.60 × 10-19 C)

A straight wire is carrying a current of 2.0 A. It is placed at an angle of 60° with respect to a magnetic field of strength 0.20 T. If the wire experiences a force of 0.40 N, what is the length of the wire?

A straight 1.0-m long wire is carrying a current. The wire is placed perpendicular to a magnetic field of strength 0.20 T. If the wire experiences a force of 0.60 N, what is the current in the wire?

What is the strength of the magnetic field at the center of a circular loop of wire of diameter 8.0 cm when a current of 2.0 A flows in the wire? (μ0 = 4π × 10-7 T ∙ m/A)

The magnetic field at point P due to a 2.0-A current flowing in a long, straight, thin wire is 8.0 μT. How far is point P from the wire? (μ0 = 4π × 10-7 T ∙ m/A)

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 Earth's magnetic field of about 5.0 × 10-5 T? (μ0 = 4π × 10-7 T ∙ m/A)

An ideal solenoid with 400 turns has a radius of 0.040 m and is 40 cm long. If this solenoid carries a current of 12 A, what is the magnitude of the magnetic field at the center of the solenoid? (μ0 = 4π × 10-7 T ∙ m/A)

At point P the magnetic field due to a long straight wire carrying a current of 2.0 A is 1.2 µT. How far is P from the wire? (μ0 = 4π × 10-7 T ∙ m/A)

An ideal solenoid having a coil density of 5000 turns per meter is 10 cm long and carries a current of 4.0 A. What is the strength of the magnetic field at its center?

A flat circular loop of wire is in a uniform magnetic field of 0.30 T. The diameter of the loop is 1.0 m, and a 2.0-A current flows in it. What is the magnitude of the magnetic torque on the loop when the plane of the loop is parallel to the magnetic field?

A long straight wire has a constant current flowing to the right. A rectangular metal loop is situated above the wire, and also has a constant current flowing through it, as shown in the figure. Which one of the following statements is true?

A proton moving with a velocity of 4.0 × 104 m/s enters a magnetic field of 0.20 T. If the angle between the velocity of the proton and the direction of the magnetic field is 60°, what is the magnitude of the magnetic force on the proton? (e = 1.60 × 10-19C)

A negatively-charged particle moves across a constant uniform magnetic field that is perpendicular to the velocity of the particle. The magnetic force on this particle

An electron traveling toward the magnetic north with speed 400 km/s enters a region where the earth's magnetic field has the magnitude 5.0 × 10-5 T and is directed downward at 45° below horizontal. What magnitude magnetic force acts on the electron? (e = 1.60 × 10-19C)

An ideal solenoid having 200 turns and carrying a current of 2.0 A is 25 cm long. What is the magnitude of the magnetic field at the center of the solenoid? (μ0 = 4π × 10-7 T ∙ m/A)

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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 that is 0.60 m from the origin along the x-axis? (μ₀ = 4π × 10^-7 T ∙ m/A)

A doubly charged ion with speed 6.9 × 10⁶ m/s enters a uniform 0.80-T magnetic field, traveling perpendicular to the field. Once in the field, it moves in a circular arc of radius 30 cm. What is the mass of this ion? (e = 1.60 × 10^-19 C)

What is the strength of the magnetic field at the center of a circular loop of wire of diameter 8.0 cm when a current of 2.0 A flows in the wire? (μ₀ = 4π × 10^-7 T ∙ m/A)

The magnetic field at point P due to a 2.0-A current flowing in a long, straight, thin wire is 8.0 μT. How far is point P from the wire? (μ₀ = 4π × 10^-7 T ∙ m/A)

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 Earth's magnetic field of about 5.0 × 10^-5 T? (μ₀ = 4π × 10^-7 T ∙ m/A)

An ideal solenoid with 400 turns has a radius of 0.040 m and is 40 cm long. If this solenoid carries a current of 12 A, what is the magnitude of the magnetic field at the center of the solenoid? (μ₀ = 4π × 10^-7 T ∙ m/A)

At point P the magnetic field due to a long straight wire carrying a current of 2.0 A is 1.2 µT. How far is P from the wire? (μ₀ = 4π × 10^-7 T ∙ m/A)

A proton moving with a velocity of 4.0 × 10⁴ m/s enters a magnetic field of 0.20 T. If the angle between the velocity of the proton and the direction of the magnetic field is 60°, what is the magnitude of the magnetic force on the proton? (e = 1.60 × 10^-19C)

An electron traveling toward the magnetic north with speed 400 km/s enters a region where the earth's magnetic field has the magnitude 5.0 × 10^-5 T and is directed downward at 45° below horizontal. What magnitude magnetic force acts on the electron? (e = 1.60 × 10^-19C)

An ideal solenoid having 200 turns and carrying a current of 2.0 A is 25 cm long. What is the magnitude of the magnetic field at the center of the solenoid? (μ₀ = 4π × 10^-7 T ∙ m/A)