Question 1

At a particular instant,an electron moves toward the east in a uniform $\vec { B }$ field that is directed straight downward.The magnetic force exerted 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 charged particle moving along the +x-axis enters a uniform $\vec { B }$ field pointing along the +z-axis.Because of an electric field along the +y-axis,the charge particle does not change velocity.What is the sign of this particle?

Accepted Answer

A) positive 
B) negative 
C) The particle could be either positive or negative. 
D) None of the above choices is correct. 
A) positive 
B) negative 
C) The particle could be either positive or negative. 
D) None of the above choices is correct.

Question 3

Two long parallel wires are placed side-by-side on a horizontal table.If the wires carry current in opposite directions,

Accepted Answer

A) one wire is lifted slightly while the other wire is forced downward against the table's surface. 
B) both wires are lifted slightly. 
C) the wires pull toward each other. 
D) the wires push away from each other. 
A) one wire is lifted slightly while the other wire is forced downward against the table's surface. 
B) both wires are lifted slightly. 
C) the wires pull toward each other. 
D) the wires push away from each other.

Question 4

A flat circular coil has 200 identical loops of very thin wire.Each loop has an area of 0.12 m2 and carries 0.50 A of current.This coil is placed in a $\vec { B }$ field of 0.050 T oriented at 30° to the plane of the loop.What is the magnitude of the magnetic torque exerted on the coil?

Accepted Answer

A) 0.25 N ∙ m 
B) 0.52 N ∙ m 
C) 2.5 N ∙ m 
D) 5.2 N ∙ m 
A) 0.25 N ∙ m 
B) 0.52 N ∙ m 
C) 2.5 N ∙ m 
D) 5.2 N ∙ m

Question 5

Two long parallel wires that are 0.40 m apart carry currents of 10 A in opposite directions.What is the magnitude of the $\vec { B }$ 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) 3.3 µT 
B) 6.7 µT 
C) 33 µT 
D) 67 µT 
A) 3.3 µT 
B) 6.7 µT 
C) 33 µT 
D) 67 µT

Question 6

An electron is moving to the right,as shown in the figure.Suddenly it encounters uniform magnetic field pointing out of the page.Which one of the three paths shown will it follow in the field?

Accepted Answer

A) path a 
B) path b 
C) path c 
A) path a 
B) path b 
C) path c

Question 7

A wire along the z-axis carries a current of 4.9 A in the +z direction.Find the magnitude and direction of the force exerted on a 3.3-cm long length of this wire by a uniform magnetic field with the $\vec { B }$ field vector pointing in the -x direction having a magnitude $0.43 \mathrm {~T}$

Accepted Answer

0.070 N,-y

Question 8

A proton travels at a speed of 5.0 × 107 m/s through a 1.0-T $\vec { B }$ field.What is the magnitude of the magnetic force exerted by the field on the proton if the angle between the proton's velocity and the $\vec { B }$ field vector is 30°? (e = 1.60 × 10-19C)

Accepted Answer

A) 2.0 × 10-14 N 
B) 4.0 × 10-14 N 
C) 2.0 × 10-12 N 
D) 4.0 × 10-12 N 
A) 2.0 × 10-14 N 
B) 4.0 × 10-14 N 
C) 2.0 × 10-12 N 
D) 4.0 × 10-12 N

Question 9

Alpha particles,each having a charge of +2e and a mass of 6.64 ×10-27 kg,are accelerated in a uniform 0.80-T magnetic field to a final orbit radius of 0.30 m.The $\vec { B }$ field is perpendicular to the velocity of the particles.How long does it take an alpha particle to make one complete circle in the final orbit? (e = 1.60 × 10-19C)

Accepted Answer

A) 0.15 μs 
B) 0.25 μs 
C) 0.33 μs 
D) 0.40 μs 
A) 0.15 μs 
B) 0.25 μs 
C) 0.33 μs 
D) 0.40 μs

Question 10

A proton is accelerated from rest through 0.50 kV.It then enters a uniform magnetic field of 0.30 T that is oriented perpendicular to its direction of motion.
(a)What is the radius of the path the proton follows in the magnetic field?
(b)How long does it take the proton to make one complete circle in the magnetic field?.

Accepted Answer

(a)11 mm

Question 11

A long straight wire carrying a 4-A current is placed along the x-axis as shown in the figure.What is the direction of the $\vec { B }$ field at a point P due to this wire?

Accepted Answer

A) into the plane of the page 
B) out of the plane of the page 
C) along the -x-axis 
D) along the +x-axis 
E) along the +y-axis 
A) into the plane of the page 
B) out of the plane of the page 
C) along the -x-axis 
D) along the +x-axis 
E) along the +y-axis

Question 12

A wire is carrying current vertically downward.What is the direction of the force exerted on this wire due to Earth's magnetic field?

Accepted Answer

A) horizontally towards the north 
B) horizontally towards the south 
C) horizontally towards the east 
D) horizontally towards the west 
E) vertically upward 
A) horizontally towards the north 
B) horizontally towards the south 
C) horizontally towards the east 
D) horizontally towards the west 
E) vertically upward

Question 13

Two long parallel wires placed side-by-side on a horizontal table carry identical current straight toward you.From your point of view,the $\vec { B }$ field at a point exactly 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 14

The $\vec { B }$ field at a distance of 2 cm from a long straight current-carrying wire is 4 μT.What is the $\vec { B }$ field at a distance of 4 cm from this wire?

Accepted Answer

A) 2 μT 
B) 4 μT 
C) 6 μT 
D) 8 μT 
E) 10 μT 
A) 2 μT 
B) 4 μT 
C) 6 μT 
D) 8 μT 
E) 10 μT

Question 15

A negatively-charged particle moves across a constant uniform $\vec { B }$ field that is perpendicular to the velocity of the particle.The magnetic force exerted 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 16

Consider two current-carrying circular loops.Both are made from one strand of wire and both carry the same current,but one has twice the radius of the other.If the $\vec { B }$ field at the center of the smaller loop is $\vec { B }$ 1,what is the $\vec { B }$ field strength at the center of the larger loop?

Accepted Answer

A) 8B1 
B) 4B1 
C) 2B1 
D) B1/2 
E) B1/4 
A) 8B1 
B) 4B1 
C) 2B1 
D) B1/2 
E) B1/4

Question 17

A rigid rectangular loop,measuring 0.30 m by 0.40 m,carries a current of 5.5 A,as shown in the figure.A uniform external $\vec { B }$ field of magnitude 2.9 T in the -x direction is present.Segment CD is in the xz-plane and forms a 35° angle with the z-axis,as shown.What is the magnitude of the torque that the magnetic field exerts on the loop?

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 
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 18

A long,straight wire carrying a current is placed along the y-axis.If the direction of the current is in the +y direction,what is the direction of the $\vec { B }$ field due to this wire as you view it in such a way that the current is coming directly toward you?

Accepted Answer

A) clockwise, around the x-axis 
B) counterclockwise, around the x-axis 
C) counterclockwise, around the z-axis 
D) counterclockwise, around the y-axis 
E) clockwise, around the y-axis 
A) clockwise, around the x-axis 
B) counterclockwise, around the x-axis 
C) counterclockwise, around the z-axis 
D) counterclockwise, around the y-axis 
E) clockwise, around the y-axis

Question 19

A flat rectangular loop of wire is placed between the poles of a magnet,as shown in the figure.It has dimensions w = 0.60 m and L = 1.0 m,and carries a current I = 2.0 A in the direction shown.The $\vec { B }$ field due to the magnet is uniform and of magnitude 0.80 T.The loop rotates in the magnetic field and at one point the plane of the loop is parallel to the field.At that instant,what is the magnitude of the torque exerted on the wire by the magnetic field?

Accepted Answer

A) 0.00 N ∙ m 
B) 0.40 N ∙ m 
C) 0.48 N ∙ m 
D) 0.83 N ∙ m 
E) 0.96 N ∙ m 
A) 0.00 N ∙ m 
B) 0.40 N ∙ m 
C) 0.48 N ∙ m 
D) 0.83 N ∙ m 
E) 0.96 N ∙ m

Question 20

If a calculated quantity has units of $\frac { \mathrm { N } } { \mathrm { A } \cdot \mathrm { m } }$ ,that quantity could be

Accepted Answer

A) an $\vec { E }$ field. 
B) an electric potential. 
C) μ0. 
D) a $\vec { B }$ field. 
E) a magnetic torque. 
A) an $\vec { E }$ field. 
B) an electric potential. 
C) μ0. 
D) a $\vec { B }$ field. 
E) a magnetic torque.

Exam 18: Magnetism

At a particular instant,an electron moves toward the east in a uniform B⃗\vec { B }B field that is directed straight downward.The magnetic force exerted on it is

A charged particle moving along the +x-axis enters a uniform B⃗\vec { B }B field pointing along the +z-axis.Because of an electric field along the +y-axis,the charge particle does not change velocity.What is the sign of this particle?

Two long parallel wires are placed side-by-side on a horizontal table.If the wires carry current in opposite directions,

A flat circular coil has 200 identical loops of very thin wire.Each loop has an area of 0.12 m2 and carries 0.50 A of current.This coil is placed in a B⃗\vec { B }B field of 0.050 T oriented at 30° to the plane of the loop.What is the magnitude of the magnetic torque exerted on the coil?

Two long parallel wires that are 0.40 m apart carry currents of 10 A in opposite directions.What is the magnitude of the B⃗\vec { B }B 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)

An electron is moving to the right,as shown in the figure.Suddenly it encounters uniform magnetic field pointing out of the page.Which one of the three paths shown will it follow in the field?

A proton travels at a speed of 5.0 × 107 m/s through a 1.0-T B⃗\vec { B }B field.What is the magnitude of the magnetic force exerted by the field on the proton if the angle between the proton's velocity and the B⃗\vec { B }B field vector is 30°? (e = 1.60 × 10-19C)

A long straight wire carrying a 4-A current is placed along the x-axis as shown in the figure.What is the direction of the B⃗\vec { B }B field at a point P due to this wire?

A wire is carrying current vertically downward.What is the direction of the force exerted on this wire due to Earth's magnetic field?

Two long parallel wires placed side-by-side on a horizontal table carry identical current straight toward you.From your point of view,the B⃗\vec { B }B field at a point exactly between the two wires

The B⃗\vec { B }B field at a distance of 2 cm from a long straight current-carrying wire is 4 μT.What is the B⃗\vec { B }B field at a distance of 4 cm from this wire?

A negatively-charged particle moves across a constant uniform B⃗\vec { B }B field that is perpendicular to the velocity of the particle.The magnetic force exerted on this particle

A long,straight wire carrying a current is placed along the y-axis.If the direction of the current is in the +y direction,what is the direction of the B⃗\vec { B }B field due to this wire as you view it in such a way that the current is coming directly toward you?

If a calculated quantity has units of NA⋅m\frac { \mathrm { N } } { \mathrm { A } \cdot \mathrm { m } }A⋅mN​ ,that quantity could be

Introduction

Kinematics: Motion in One Dimension

Newtonian Mechanics

Applying Newtons Laws

Circular Motion

Impulse and Linear Momentum

Work and Energy

Extended Bodies at Rest

Rotational Motion

Gases

Static Fluids

Fluids in Motion

First Law of Thermodynamics

Second Law of Thermodynamics

Electric Charge force and Energy

The Electric Field

Dc Circuits

Electromagnetic Induction

Vibrational Motion

Mechanical Waves

Reflection and Refraction

Mirrors and Lenses

Wave Optics

Electromagnetic Waves

Special Relativity

Quantum Optics

Atomic Physics

Nuclear Physics

Particle Physics

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