Question 1

A long straight wire on the z-axis carries a current of 6.0 A in the positive direction. A circular loop in the xy-plane, of radius 10 cm, carries a 1.0-A current, as shown in the figure. Point P, at the center of the loop, is 25 cm from the z-axis. An electron is projected from P with a velocity of 1.0 × 106 m/s in the negative x-direction. What is the y component of the force on the electron? (e = 1.60 × 10-19 C, μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  -1.0 × 10-18 N 
B)  +1.0 × 10-18 N 
C)  -2.0 × 10-18 N 
D)  +2.0 × 10-18 N 
E)  zero

Question 2

A rigid rectangular loop, which measures 0.30 m by 0.40 m, carries a current of 5.5 A, as shown in the figure. A uniform external magnetic field of magnitude 2.9 T in the negative x direction is present. Segment CD is in the xz-plane and forms a 35° angle with the z-axis, as shown. Find the magnitude of the external torque needed to keep the loop in static equilibrium.

Accepted Answer

A)  1.1 N ∙ m 
B)  0.73 N ∙ m 
C)  1.3 N ∙ m 
D)  1.4 N ∙ m 
E)  1.6 N ∙ m

Question 3

Two coaxial circular coils of radius R = 15 cm, each carrying 4.0 A in the same direction, are positioned a distance d = 20 cm apart, as shown in the figure. Calculate the magnitude of the magnetic field halfway between the coils along the line connecting their centers. (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  0.90 × 10-5 T 
B)  3.9 × 10-5 T 
C)  1.9 × 10-5 T 
D)  6.3 × 10-5 T 
E)  9.2 × 10-5 T

Question 4

A wire carrying a current is shaped in the form of a circular loop of radius 3.0 mm. If the magnetic field strength that this current produces at the center of the loop is 1.1 mT, what is the magnitude of the current that flows through the wire? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  5.3 A 
B)  16 A 
C)  9.1 A 
D)  23 A

Question 5

A particle with charge -5.00 C initially moves at  = (1.00 
+ 7.00 
) m/s. If it encounters a magnetic field 
Find the magnetic force vector on the particle.

Accepted Answer

A)  (-350  + 50.0  ) N 
B)  (-350  - 50.0  ) N 
C)  (350  + 50.0  ) N 
D)  (350  - 50.0  ) N

Question 6

A charged particle is moving with speed v perpendicular to a uniform magnetic field. A second identical charged particle is moving with speed 2v perpendicular to the same magnetic field. If the frequency of revolution of the first particle is f, the frequency of revolution of the second particle is

Accepted Answer

A)  f. 
B)  2f. 
C)  4f. 
D)  f /2. 
E)  f /4.

Question 7

A wire segment 1.2 m long carries a current I = 3.5 A, and is oriented as shown in the figure. The +x-axis points directly into the page. A uniform magnetic field of magnitude 0.50 T pointing toward the -x direction is present as shown. What is the magnetic force vector on the wire segment?

Accepted Answer

A)  (+1.1  - 1.8  ) N 
B)  (-1.1  + 1.8  ) N 
C)  (-1.1  - 1.8  ) N 
D)  (+1.8  - 1.1  ) N 
E)  (-1.8  + 1.1  ) N

Question 8

A cylindrical insulated wire of diameter 5.0 mm is tightly wound 200 times around a cylindrical core to form a solenoid with adjacent coils touching each other. When a 0.10 A current is sent through the wire, what is the magnitude of the magnetic field on the axis of the solenoid near its center? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  6.6 × 10-5 T 
B)  2.5 × 10-5 T 
C)  1.3 × 10-5 T 
D)  3.6 × 10-5 T 
E)  9.8 × 10-5 T

Question 9

A very long, hollow, thin-walled conducting cylindrical shell (like a pipe) of radius R carries a current along its length uniformly distributed throughout the thin shell. Which one of the graphs shown in the figure most accurately describes the magnitude B of the magnetic field produced by this current as a function of the distance r from the central axis?

Accepted Answer

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

Question 10

A very long, solid, conducting cylinder of radius R carries a current along its length uniformly distributed throughout the cylinder. Which one of the graphs shown in the figure most accurately describes the magnitude B of the magnetic field produced by this current as a function of the distance r from the central axis?

Accepted Answer

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

Question 11

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 toward you, and the wire on your left carries current away from you. From your point of view, the magnetic field at the 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.

Question 12

Two long parallel wires carry currents of 10 A in opposite directions. They are separated by 40 cm. What is the magnitude of 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? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  1.5 µT 
B)  3.3 µT 
C)  6.7 µT 
D)  33 µT 
E)  67 µT

Question 13

A solenoid is wound with 970 turns on a form 4.0 cm in diameter and 50 cm long. The windings carry a current I in the sense that is shown in the figure. The current produces a magnetic field, of magnitude 4.3 mT, near the center of the solenoid. Find the current in the solenoid windings. (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  1.8 A 
B)  1.5 A 
C)  1.3 A 
D)  2.2 A 
E)  2.0 A

Question 14

A doubly charged ion (charge 2e) with velocity 6.9 × 106 m/s moves in a circular path of diameter 60.0 cm in a magnetic field of 0.80 T in a mass spectrometer. What is the mass of this ion? (e = 1.60 × 10-19C)

Accepted Answer

A)  11 × 10-27 kg 
B)  6.7 × 10-27 kg 
C)  4.5 × 10-27 kg 
D)  3.3 × 10-27 kg

Question 15

A circular coil of wire of 200 turns and diameter 2.0 cm carries a current of 4.0 A. It is placed in a magnetic field of 0.70 T with the plane of the coil making an angle of 30° with the magnetic field. What is the magnetic torque on the coil?

Accepted Answer

A)  0.15 N ∙ m 
B)  0.088 N ∙ m 
C)  0.29 N ∙ m 
D)  0.40 N ∙ m 
E)  0.076 N ∙ m

Question 16

A very long thin wire produces a magnetic field of 0.0050 × 10-4 T at a distance of 3.0 mm. from the central axis of the wire. What is the magnitude of the current in the wire? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  7.5 mA 
B)  1.7 mA 
C)  3300 mA 
D)  24,000 mA

Question 17

The figure shows two long wires carrying equal currents I1 and I2 flowing in opposite directions. Which of the arrows labeled A through D correctly represents the direction of the magnetic field due to the wires at a point located at an equal distance d from each wire?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  The magnetic field is zero at that point.

Question 18

A proton, with mass 1.67 × 10^-27 kg and charge +1.6 × 10^-19 C, is sent with velocity 7.1 × 10⁴ m/s in the +x direction into a region where there is a uniform electric field of magnitude 730 V/m in the +y direction. What are the magnitude and direction of the uniform magnetic field in the region, if the proton is to pass through undeflected? Assume that the magnetic field has no x-component and neglect gravitational effects.

Accepted Answer

The answer of A proton, with mass 1.67 × 10^-27...

Question 19

A long straight very thin wire on the y-axis carries a 10-A current in the positive y-direction. A circular loop 0.50 m in radius, also of very thin wire and lying in the yz-plane, carries a 9.0-A current, as shown. Point P is on the positive x-axis, at a distance of 0.50 m from the center of the loop. What is the magnetic field vector at point P due to these two currents? (μ0 = 4π × 10-7 T ∙ m/A)

Accepted Answer

A)  zero 
B)  -8.0 × 10-6 T  
C)  (+4.0 × 10-6 T)  - (4.0 × 10-6 T)  
D)  (-4.0 × 10-6 T)  - (4.0 × 10-6 T)  
E)  (-4.0 × 10-6 T)  - (8.0 × 10-6 T)

Question 20

Ions having equal charges but masses of M and 2M are accelerated through the same potential difference and then enter a uniform magnetic field perpendicular to their path. If the heavier ions follow a circular arc of radius R, what is the radius of the arc followed by the lighter?

Accepted Answer

A)  4R 
B)  3R 
C)   R 
D)  R/  
E)  R/2

Exam 32: The Magnetic Field

A wire carrying a current is shaped in the form of a circular loop of radius 3.0 mm. If the magnetic field strength that this current produces at the center of the loop is 1.1 mT, what is the magnitude of the current that flows through the wire? (μ₀ = 4π × 10^-7 T ∙ m/A)

A particle with charge -5.00 C initially moves at = (1.00 + 7.00 ) m/s. If it encounters a magnetic field Find the magnetic force vector on the particle.

A charged particle is moving with speed v perpendicular to a uniform magnetic field. A second identical charged particle is moving with speed 2v perpendicular to the same magnetic field. If the frequency of revolution of the first particle is f, the frequency of revolution of the second particle is

A wire segment 1.2 m long carries a current I = 3.5 A, and is oriented as shown in the figure. The +x-axis points directly into the page. A uniform magnetic field of magnitude 0.50 T pointing toward the -x direction is present as shown. What is the magnetic force vector on the wire segment?

Two long parallel wires carry currents of 10 A in opposite directions. They are separated by 40 cm. What is the magnitude of 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? (μ₀ = 4π × 10^-7 T ∙ m/A)

A doubly charged ion (charge 2e) with velocity 6.9 × 10⁶ m/s moves in a circular path of diameter 60.0 cm in a magnetic field of 0.80 T in a mass spectrometer. What is the mass of this ion? (e = 1.60 × 10^-19C)

A circular coil of wire of 200 turns and diameter 2.0 cm carries a current of 4.0 A. It is placed in a magnetic field of 0.70 T with the plane of the coil making an angle of 30° with the magnetic field. What is the magnetic torque on the coil?

A very long thin wire produces a magnetic field of 0.0050 × 10^-4 T at a distance of 3.0 mm. from the central axis of the wire. What is the magnitude of the current in the wire? (μ₀ = 4π × 10^-7 T ∙ m/A)

The figure shows two long wires carrying equal currents I₁ and I₂ flowing in opposite directions. Which of the arrows labeled A through D correctly represents the direction of the magnetic field due to the wires at a point located at an equal distance d from each wire?

Ions having equal charges but masses of M and 2M are accelerated through the same potential difference and then enter a uniform magnetic field perpendicular to their path. If the heavier ions follow a circular arc of radius R, what is the radius of the arc followed by the lighter?