Question 1

A stationary positive charge +Q is located in a magnetic field B,which is directed toward the right as indicated.The direction of the magnetic force on Q is:

Accepted Answer

A) toward the right. 
B) up. 
C) down. 
D) There is no magnetic force.

Question 2

A circular coil (radius = 0.25 m)has 143 turns and is in a uniform magnetic field.If the orientation of the coil is varied through all possible positions,the maximum torque on the coil by magnetic forces is 0.29 N⋅m when the current in the coil is 2.7 mA.What is the magnitude of the magnetic field?

Accepted Answer

A) 5.47 T 
B) 0.304 T 
C) 3.83 T 
D) 137 T

Question 3

A 198-m-long wire carrying a current of 3.5 A will be accompanied by a magnetic field of what strength at a distance of 0.054 m from the wire? (magnetic permeability in empty space µ0 = 4π × 10−7 T⋅m/A)

Accepted Answer

A) 4.1E-5 T 
B) 8.3E-6 T 
C) 1.3E-5 T 
D) 6.5E-6 T 
E) zero

Question 4

A proton moves across the Earth's equator in a northeasterly direction.At this point the Earth's magnetic field has a direction due north and is parallel to the surface.What is the direction of the force acting on the proton at this instant?

Accepted Answer

A) toward the northwest 
B) out of the Earth's surface 
C) into the Earth's surface 
D) toward the northeast

Question 5

Two parallel conductors are carrying currents in the opposite direction.The currents are non-zero and not necessarily equal.The magnitude of the magnetic field midway between them is 40 μT.If one of the currents then has its direction reversed,what is the resulting magnitude of the magnetic field midway between them?

Accepted Answer

A) a value greater than 40 μT 
B) 40 μT 
C) a value less than 40 μT 
D) It could be any value.

Question 6

A charged particle moving perpendicular to a magnetic field has a magnet force on it.But when an observer moves with the particle,so that the particle has a relative velocity of zero with respect to the observer,one would expect there would be no magnetic force.Yet there is still a force.If it is not a magnetic force,then what is the source of this force?

Accepted Answer

A) It is an electrical force. 
B) It is due to the ether. 
C) It is a gravitational force. 
D) It is something other than any of the above.

Question 7

​A proton is circling the Earth above the magnetic equator,where Earth's magnetic field is directed horizontally north and has a magnitude of 4.00 × 10-8 T.If the proton is moving at a speed of 2.7 × 107 m/s,how far above the surface of the Earth is the proton? Earth's radius is 6.38 × 106 m,a proton's mass is 1.67 × 10-27 kg,and its charge is 1.6 × 10-19 C.

Accepted Answer

A) ​7.05E+6 m 
B) ​1.34E+7 m 
C) ​1.03E+8 m 
D) ​6.65E+5 m

Question 8

Which of the following locations has the smallest (in magnitude)magnetic declination?

Accepted Answer

A) Washington state 
B) the South Carolina - Georgia border 
C) the San Francisco - Oakland area 
D) western Colorado

Question 9

Two long parallel wires 79.4 cm apart are carrying currents of 12.6 A and 28.1 A in the opposite direction.What is the magnitude of the magnetic field halfway between the wires?

Accepted Answer

A) 7.81E-6 T 
B) 6.35E-6 T 
C) 2.05E-5 T 
D) 1.42E-5 T 
E) 1.03E-5 T

Question 10

When a magnetic field causes a charged particle to move in a circular path,the only quantity listed below which the magnetic force changes significantly as the particle goes around in a circle is the particle's:

Accepted Answer

A) energy. 
B) momentum. 
C) radius for the circle. 
D) time to go around the circle once.

Question 11

An 8.00-cm-long piece of wire is formed into a square,and carries a clockwise current of 0.150 A.The loop is placed inside a solenoid,and the plane of the loop is perpendicular to the solenoid's magnetic field.The solenoid carries a counterclockwise current of 17.0 A,and has 25 turns per centimeter.What is the force on each side of the loop?

Accepted Answer

A) 1.07E-5 N 
B) 6.41E-4 N 
C) 1.60E-4 N 
D) 4.27E-3 N

Question 12

A superconducting wire carries a current of 7.0 kA.Find the magnetic field at a distance of 1.5 m from the wire.(µ0 = 4π × 10−7 T⋅m/A)

Accepted Answer

A) 9.3E-4 T 
B) 3.0E-4 T 
C) 2.9E-3 T 
D) 1.5E-3 T 
E) 5.9E-3 T

Question 13

A proton and an alpha particle are moving perpendicular to a uniform magnetic field with the same speed.If the velocity of the proton is at an angle of 20° with respect to the magnetic field direction,at what angle to the magnetic field direction would the alpha particle be moving if it experiences the same magnitude acceleration as the proton? The alpha particle has 4 times the mass of the proton and twice its charge.

Accepted Answer

A) 43° 
B) 10° 
C) 62° 
D) 9.8°

Question 14

There is a current I flowing in a clockwise direction in a square loop of wire that is in the plane of the paper.If the magnetic field B is toward the right,and if each side of the loop has length L,then the net magnetic force acting on the loop is

Accepted Answer

A) 2ILB. 
B) ILB. 
C) IBL2. 
D) zero.

Question 15

The magnetic force on a charged particle moving at a constant speed in a uniform magnetic field will be halved when the angle between the velocity of the particle and the direction of the magnetic field changes from 25.0° to

Accepted Answer

A) 50.0°. 
B) 12.5°. 
C) 57.7°. 
D) 12.2°.

Question 16

A current-carrying wire of length 52.0 cm is positioned perpendicular to a uniform magnetic field.If the current is 15.0 A and it is determined that there is a resultant force of 2.3 N on the wire due to the interaction of the current and field,what is the magnetic field strength?

Accepted Answer

A) 0.29 T 
B) 0.029 T 
C) 0.020 T 
D) 0.38 T 
E) 0.18 T

Question 17

Superconductors can carry very large currents with no resistance.If a superconducting wire is formed into a solenoid of length 20.0 cm with 691 turns,what is the magnetic field inside the solenoid when the current is 5.38 kA? (µ0 = 4π × 10−7 T⋅m/A)

Accepted Answer

A) 1.86 T 
B) 0.934 T 
C) 46.7 T 
D) 23.4 T 
E) 73.4 T

Question 18

A proton and an alpha particle are moving perpendicular to a uniform magnetic field with the same speeds.If the velocity of the proton is at an angle of 20° with respect to the magnetic field direction,at what angle to the magnetic field direction would the alpha particle be moving if it experiences the same magnitude magnetic force as the proton? The alpha particle has 4 times the mass of the proton and twice its charge.

Accepted Answer

A) 10° 
B) 62° 
C) 43° 
D) 9.8°

Question 19

Two long parallel wires 10.0 cm apart carry currents of 3.0 A and 2.9 A in the same direction.Is there any point between the two wires where the magnetic field is zero?

Accepted Answer

A) yes,midway between the wires 
B) yes,4.9 cm from the 3.0-A wire 
C) yes,5.1 cm from the 3.0-A wire 
D) yes,5.1 cm from the 2.9-A wire 
E) no.

Question 20

Two parallel conductors each of 0.34 m length,separated by 6.4 × 10−3 m and carrying 4.8 A in opposite directions,will experience what type and magnitude of mutual force? (magnetic permeability in empty space µ0 = 4π × 10−7 T⋅m/A)

Accepted Answer

A) attractive,2.1E-3 N 
B) repulsive,2.1E-3 N 
C) attractive,2.4E-4 N 
D) repulsive,2.4E-4 N 
E) zero

Exam 19: Magnetism

A stationary positive charge +Q is located in a magnetic field B,which is directed toward the right as indicated.The direction of the magnetic force on Q is:

A 198-m-long wire carrying a current of 3.5 A will be accompanied by a magnetic field of what strength at a distance of 0.054 m from the wire? (magnetic permeability in empty space µ₀ = 4π × 10−⁷ T⋅m/A)

A proton moves across the Earth's equator in a northeasterly direction.At this point the Earth's magnetic field has a direction due north and is parallel to the surface.What is the direction of the force acting on the proton at this instant?

Which of the following locations has the smallest (in magnitude) magnetic declination?

Two long parallel wires 79.4 cm apart are carrying currents of 12.6 A and 28.1 A in the opposite direction.What is the magnitude of the magnetic field halfway between the wires?

When a magnetic field causes a charged particle to move in a circular path,the only quantity listed below which the magnetic force changes significantly as the particle goes around in a circle is the particle's:

A superconducting wire carries a current of 7.0 kA.Find the magnetic field at a distance of 1.5 m from the wire.(µ₀ = 4π × 10−⁷ T⋅m/A)

There is a current I flowing in a clockwise direction in a square loop of wire that is in the plane of the paper.If the magnetic field B is toward the right,and if each side of the loop has length L,then the net magnetic force acting on the loop is

The magnetic force on a charged particle moving at a constant speed in a uniform magnetic field will be halved when the angle between the velocity of the particle and the direction of the magnetic field changes from 25.0° to

A current-carrying wire of length 52.0 cm is positioned perpendicular to a uniform magnetic field.If the current is 15.0 A and it is determined that there is a resultant force of 2.3 N on the wire due to the interaction of the current and field,what is the magnetic field strength?

Superconductors can carry very large currents with no resistance.If a superconducting wire is formed into a solenoid of length 20.0 cm with 691 turns,what is the magnetic field inside the solenoid when the current is 5.38 kA? (µ₀ = 4π × 10−⁷ T⋅m/A)

Two long parallel wires 10.0 cm apart carry currents of 3.0 A and 2.9 A in the same direction.Is there any point between the two wires where the magnetic field is zero?

Two parallel conductors each of 0.34 m length,separated by 6.4 × 10−³ m and carrying 4.8 A in opposite directions,will experience what type and magnitude of mutual force? (magnetic permeability in empty space µ₀ = 4π × 10−⁷ T⋅m/A)