Question 1

Two parallel wires are separated by 0.43 m.Wire A carries 3.3 A and Wire B carries 8.3 A,both currents in the same direction.The force on 0.90 m of Wire A is:

Accepted Answer

A)  1.1 × 10-5 N. 
B)  1.4 × 10-5 N. 
C)  0.35 × 10-5 N. 
D)  0.14 × 10-5 N. 
E)  ​3.6 × 10-5 N. 
A)  1.1 × 10-5 N. 
B)  1.4 × 10-5 N. 
C)  0.35 × 10-5 N. 
D)  0.14 × 10-5 N. 
E)  ​3.6 × 10-5 N.

Question 2

An electron is moving at a speed of 5.1 × 106 m/s at an angle of 23° with respect to a uniform magnetic field of 7.3 × 10-4 T.What is the radius of the resulting helical path? (me = 9.11 × 10-31 kg,qe = 1.6 × 10-19 C)

Accepted Answer

A)  3.7 cm 
B)  4.0 cm 
C)  3.2 cm 
D)  1.6 cm 
E)  ​3.4 cm 
A)  3.7 cm 
B)  4.0 cm 
C)  3.2 cm 
D)  1.6 cm 
E)  ​3.4 cm

Question 3

Two parallel conductors each of 0.67 m length,separated by 4.1 × 10−3 m and carrying 3.2 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,7.5 × 10−4 N 
B)  repulsive,7.5 × 10−4 N 
C)  attractive,3.3 × 10−4 N 
D)  repulsive,3.3 × 10−4 N 
E)  ​zero 
A)  attractive,7.5 × 10−4 N 
B)  repulsive,7.5 × 10−4 N 
C)  attractive,3.3 × 10−4 N 
D)  repulsive,3.3 × 10−4 N 
E)  ​zero

Question 4

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

Question 5

Two parallel conductors are carrying currents in the same 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. 
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

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 torque acting on the loop is:

Accepted Answer

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

Question 7

A current in a long,straight wire produces a magnetic field.The magnetic field lines:

Accepted Answer

A)  go out from the wire to infinity. 
B)  come in from infinity to the wire. 
C)  form circles that pass through the wire. 
D)  form circles that go around the wire. 
A)  go out from the wire to infinity. 
B)  come in from infinity to the wire. 
C)  form circles that pass through the wire. 
D)  form circles that go around the wire.

Question 8

An electron which moves with a speed of 2.5 × 104 m/s parallel to a uniform magnetic field of 0.44 T experiences a force of what magnitude? (e = 1.6 × 10−19 C)

Accepted Answer

A)  1.76E-15 N 
B)  2.82E-33 N 
C)  8.80E-16 N 
D)  9.09E-15 N 
E)  zero 
A)  1.76E-15 N 
B)  2.82E-33 N 
C)  8.80E-16 N 
D)  9.09E-15 N 
E)  zero

Question 9

A deuteron,with the same charge but twice the mass of a proton,moves with a speed of 1.7 × 105 m/s perpendicular to a uniform magnetic field of 0.36 T.Which of the paths described below would it follow? (qp = 1.6 × 10−19 C and md = 3.34 × 10−27 kg)

Accepted Answer

A)  a straight line path 
B)  a circular path of 2.5 cm radius 
C)  a circular path of 1.0 cm radius 
D)  a circular path of 0.09 cm radius 
E)  ​a circular path of 0.87 cm radius 
A)  a straight line path 
B)  a circular path of 2.5 cm radius 
C)  a circular path of 1.0 cm radius 
D)  a circular path of 0.09 cm radius 
E)  ​a circular path of 0.87 cm radius

Question 10

When an electromagnet has an iron core inserted,what happens to the strength of the magnet?

Accepted Answer

A)  It increases. 
B)  It remains the same. 
C)  It decreases. 
D)  Since it depends on the metal used in the wires of the electromagnet,any of the above. 
A)  It increases. 
B)  It remains the same. 
C)  It decreases. 
D)  Since it depends on the metal used in the wires of the electromagnet,any of the above.

Question 11

A circular current loop is placed in an external magnetic field.How is the torque related to the radius of the loop?

Accepted Answer

A)  directly proportional to radius 
B)  inversely proportional to radius 
C)  directly proportional to radius squared 
D)  inversely proportional to radius squared 
A)  directly proportional to radius 
B)  inversely proportional to radius 
C)  directly proportional to radius squared 
D)  inversely proportional to radius squared

Question 12

If a charged particle is moving in a uniform magnetic field,its path can be:

Accepted Answer

A)  a straight line. 
B)  a circle. 
C)  a helix. 
D)  any of the above. 
A)  a straight line. 
B)  a circle. 
C)  a helix. 
D)  any of the above.

Question 13

A superconducting wire carries a current of 10 kA.Find the magnetic field at a distance of 2.0 m from the wire.(µ0 = 4π × 10−7 T⋅m/A)

Accepted Answer

A)  1.0 × 10−3 T 
B)  0.32 × 10−3 T 
C)  3.1 × 10−2 T 
D)  1.6 × 10−2 T 
E)  ​6.3 × 10−3 T 
A)  1.0 × 10−3 T 
B)  0.32 × 10−3 T 
C)  3.1 × 10−2 T 
D)  1.6 × 10−2 T 
E)  ​6.3 × 10−3 T

Question 14

Two insulated current-carrying straight wires of equal length are arranged in the lab so that Wire A carries a current northward and Wire B carries a current eastward,the wires crossing at their midpoints separated only by their insulation.Which of the following statements are true?

Accepted Answer

A)  The net force on Wire B is southward. 
B)  The net force on Wire A is westward. 
C)  There are no forces in this situation. 
D)  There are forces,but the net force on each wire is zero. 
A)  The net force on Wire B is southward. 
B)  The net force on Wire A is westward. 
C)  There are no forces in this situation. 
D)  There are forces,but the net force on each wire is zero.

Question 15

The magnetic domains in a non-magnetized piece of iron are characterized by which orientation?

Accepted Answer

A)  parallel to the magnetic axis 
B)  anti-parallel (opposite direction)to the magnetic axis 
C)  random 
D)  perpendicular to the magnetic axis 
A)  parallel to the magnetic axis 
B)  anti-parallel (opposite direction)to the magnetic axis 
C)  random 
D)  perpendicular to the magnetic axis

Question 16

The force exerted on a current-carrying wire located in an external magnetic field is directly proportional to which of the following?

Accepted Answer

A)  current strength 
B)  field strength 
C)  both A and B 
D)  None of the above are valid. 
A)  current strength 
B)  field strength 
C)  both A and B 
D)  None of the above are valid.

Question 17

A proton and a deuteron are moving with equal velocities perpendicular to a uniform magnetic field.A deuteron has the same charge as the proton but has twice its mass.The ratio of the acceleration of the proton to that of the deuteron is:

Accepted Answer

A)  0.5. 
B)  1. 
C)  2. 
D)  There is no acceleration in this case. 
A)  0.5. 
B)  1. 
C)  2. 
D)  There is no acceleration in this case.

Question 18

Geophysicists today generally attribute the existence of the Earth's magnetic field to which of the following?

Accepted Answer

A)  convection currents within the liquid interior 
B)  iron ore deposits in the crust 
C)  nickel-iron deposits in the crust 
D)  solar flares 
A)  convection currents within the liquid interior 
B)  iron ore deposits in the crust 
C)  nickel-iron deposits in the crust 
D)  solar flares

Question 19

A proton moving at a speed of 3.2 × 106 m/s cuts across the lines of a magnetic field at an angle of 61°.The strength of the field is 0.63 × 10−4 T.What is the magnitude of the force acting on the proton? (qp = 1.6 × 10−19 C)

Accepted Answer

A)  1.6E-17 N 
B)  3.1E-17 N 
C)  2.8E-17 N 
D)  7.1E-9 N 
E)  ​4.5E-36 N 
A)  1.6E-17 N 
B)  3.1E-17 N 
C)  2.8E-17 N 
D)  7.1E-9 N 
E)  ​4.5E-36 N

Question 20

An electron moves through a region of crossed electric and magnetic fields.The electric field E = 3381 V/m and is directed straight down.The magnetic field B = 0.77 T and is directed to the left.For what velocity v of the electron into the paper will the electric force exactly cancel the magnetic force?

Accepted Answer

A)  4400 m/s 
B)  2600 m/s 
C)  4200 m/s 
D)  5200 m/s 
E)  ​7000 m/s 
A)  4400 m/s 
B)  2600 m/s 
C)  4200 m/s 
D)  5200 m/s 
E)  ​7000 m/s

Exam 19: Magnetism Magnets

Two parallel wires are separated by 0.43 m.Wire A carries 3.3 A and Wire B carries 8.3 A,both currents in the same direction.The force on 0.90 m of Wire A is:

An electron is moving at a speed of 5.1 × 106 m/s at an angle of 23° with respect to a uniform magnetic field of 7.3 × 10-4 T.What is the radius of the resulting helical path? (me = 9.11 × 10-31 kg,qe = 1.6 × 10-19 C)

Two parallel conductors each of 0.67 m length,separated by 4.1 × 10−3 m and carrying 3.2 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)

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 torque acting on the loop is:

A current in a long,straight wire produces a magnetic field.The magnetic field lines:

An electron which moves with a speed of 2.5 × 104 m/s parallel to a uniform magnetic field of 0.44 T experiences a force of what magnitude? (e = 1.6 × 10−19 C)

A deuteron,with the same charge but twice the mass of a proton,moves with a speed of 1.7 × 105 m/s perpendicular to a uniform magnetic field of 0.36 T.Which of the paths described below would it follow? (qp = 1.6 × 10−19 C and md = 3.34 × 10−27 kg)

When an electromagnet has an iron core inserted,what happens to the strength of the magnet?

A circular current loop is placed in an external magnetic field.How is the torque related to the radius of the loop?

If a charged particle is moving in a uniform magnetic field,its path can be:

A superconducting wire carries a current of 10 kA.Find the magnetic field at a distance of 2.0 m from the wire.(µ0 = 4π × 10−7 T⋅m/A)

Two insulated current-carrying straight wires of equal length are arranged in the lab so that Wire A carries a current northward and Wire B carries a current eastward,the wires crossing at their midpoints separated only by their insulation.Which of the following statements are true?

The magnetic domains in a non-magnetized piece of iron are characterized by which orientation?

The force exerted on a current-carrying wire located in an external magnetic field is directly proportional to which of the following?

A proton and a deuteron are moving with equal velocities perpendicular to a uniform magnetic field.A deuteron has the same charge as the proton but has twice its mass.The ratio of the acceleration of the proton to that of the deuteron is:

Geophysicists today generally attribute the existence of the Earth's magnetic field to which of the following?

A proton moving at a speed of 3.2 × 106 m/s cuts across the lines of a magnetic field at an angle of 61°.The strength of the field is 0.63 × 10−4 T.What is the magnitude of the force acting on the proton? (qp = 1.6 × 10−19 C)

Introduction

Introduction: Part A

Motion in One Dimension

Motion in One Dimension: Part A

Vectors and Two-Dimensional Motion

Vectors and Two-Dimensional Motion: Part A

The Laws of Motion

The Laws of Motion: Part A

Energy

Energy: Part A

Momentum and Collisions

Momentum and Collisions: Part A

Rotational Motion and the Law of Gravity

Rotational Motion and the Law of Gravity: Part A

Rotational Equilibrium and Rotational Dynamics

Rotational Equilibrium and Rotational Dynamics: Part A

Solids and Fluids

Solids and Fluids: Part A

Thermal Physics

Thermal Physics: Part A

Energy in Thermal Processes Heat and Internal Energy

Energy in Thermal Processes Heat and Internal Energy: Part A

The Laws of Thermodynamics Work in Thermodynamic Processes

The Laws of Thermodynamics Work in Thermodynamic Processes: Part A

Vibrations and Waves

Vibrations and Waves: Part A

Sound

Sound: Part A

Electric Forces and Electric Fields

Electric Forces and Electric Fields: Part A

Electrical Energy and Capacitance

Electrical Energy and Capacitance: Part A

Current and Resistance Electric Current

Current and Resistance Electric Current: Part A

Direct-Current Circuits Sources of EMF

Direct-Current Circuits Sources of EMF: Part A

Magnetism Magnets: Part A

Induced Voltages and Inductance

Induced Voltages and Inductance: Part A

Alternating-Current Circuits and Electromagnetic Waves

Alternating-Current Circuits and Electromagnetic Waves: Part A

Reflection and Refraction of Light

Reflection and Refraction of Light: Part A

Mirrors and Lenses

Mirrors and Lenses: Part A

Wave Optics

Wave Optics: Part A

Optical Instruments

Optical Instruments: Part A

Relativity

Relativity: Part A

Quantum Physics Blackbody Radiation and Plancks Hypothesis

Quantum Physics Blackbody Radiation and Plancks Hypothesis: Part A

Atomic Physics

Atomic Physics: Part A

Nuclear Physics

Nuclear Physics: Part A

Nuclear Energy and Elementary Particles

Nuclear Energy and Elementary Particles: Part A

Particle Collisions, Mediating Photons, and Quark Structures: Exploring the Fundamentals of Physics

Filters

An electron is moving at a speed of 5.1 × 10⁶ m/s at an angle of 23° with respect to a uniform magnetic field of 7.3 × 10^-4 T.What is the radius of the resulting helical path? (m_e = 9.11 × 10^-31 kg,q_e = 1.6 × 10^-19 C)

Two parallel conductors each of 0.67 m length,separated by 4.1 × 10−³ m and carrying 3.2 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)

An electron which moves with a speed of 2.5 × 10⁴ m/s parallel to a uniform magnetic field of 0.44 T experiences a force of what magnitude? (e = 1.6 × 10−¹⁹ C)

A deuteron,with the same charge but twice the mass of a proton,moves with a speed of 1.7 × 10⁵ m/s perpendicular to a uniform magnetic field of 0.36 T.Which of the paths described below would it follow? (q_p = 1.6 × 10−¹⁹ C and m_d = 3.34 × 10−²⁷ kg)

A superconducting wire carries a current of 10 kA.Find the magnetic field at a distance of 2.0 m from the wire.(µ₀ = 4π × 10−⁷ T⋅m/A)

A proton moving at a speed of 3.2 × 10⁶ m/s cuts across the lines of a magnetic field at an angle of 61°.The strength of the field is 0.63 × 10−⁴ T.What is the magnitude of the force acting on the proton? (q_p = 1.6 × 10−¹⁹ C)