Question 1

The apparatus in the figure consists of two parallel plates (shown on edge) and a large magnet (not shown). The field of the magnet is uniform, perpendicular to the electric field between the plates, and directed into the plane of the paper. The magnitude of  is 0.40 T. Charged particles with speeds of 5.0 *105 m/s enter this region through the slit at the left and emerge through the exit slit at the right. What magnitude and direction must the  field have so that positively charged particles entering from the left will traverse to the exit slit undeviated?

Accepted Answer

A)  2.0 *105 V/m up 
B)  2.0* 105 V/m down 
C)  1.2 * 106 V/m down 
D)  1.2 *106 V/m up 
E)  2.4 * 106 V/m down

Question 2

The region of space around a moving proton contains

Accepted Answer

A)  a gravitational field only. 
B)  a magnetic field only. 
C)  an electric field only. 
D)  both an electric and a magnetic field. 
E)  neither an electric nor a magnetic field.

Question 3

The magnetic force on a charged particle

Accepted Answer

A)  depends on the sign of the charge on the particle. 
B)  depends on the velocity of the particle. 
C)  depends on the magnetic field at the particle's instantaneous position. 
D)  is at right angles to both the velocity and the direction of the magnetic field. 
E)  is described by all of these.

Question 4

A current I flows in a wire that is oriented as shown. The vector representing the magnetic field that results in a maximum force on the wire is

Accepted Answer

A)   
B)   
C)   
D)   
E)

Question 5

A circular 10-turn coil with a radius of 5.0 cm carries a current of 5 A. It lies in the xy plane in a uniform magnetic field  = 0.05 T  + 0.12 T  . The coil rotates so that its magnetic moment, $\mu$, is aligned with the magnetic field. The potential energy of the system when the coil's magnetic moment is aligned with the field is

Accepted Answer

A)  86.3 mJ 
B)  51.1 mJ 
C)  28.2 mJ 
D)  -28.2 mJ 
E)  -51.1 mJ

Question 6

A proton with a charge +e is moving with a speed v at 50º to the direction of a magnetic field  . The component of the resulting force on the proton in the direction of  is

Accepted Answer

A)  evB sin 50º cos 50º 
B)  evB cos 50º 
C)  zero 
D)  evB sin 50º 
E)  None of these is correct.

Question 7

An electron is accelerated from rest by an electric field. After the acceleration, the electron is injected into a uniform magnetic field of 1.27 * 10-3 T. The velocity of the electron and the magnetic field lines are perpendicular to one another. The electron remains in the magnetic field for 5.00 * 10-9 s. The angle between the initial electron velocity and the final electron velocity is

Accepted Answer

A)  1.1 rad 
B)  5.8 * 10-2 rad 
C)  8.68* 10-2 rad 
D)  6.5 * 10-2 rad 
E)  2.3 rad

Question 8

The radius of curvature of the path of a charged particle moving perpendicular to a magnetic field is given by

Accepted Answer

A)  qE/m 
B)  Bm/(qv) 
C)  Bv/(qm) 
D)  mv/(q
B)  
E)  Bq/(mv)

Question 9

A uniform magnetic field is parallel to and in the direction of the positive z axis. For an electron to enter this field and not be deflected by the field, the electron must be traveling in which direction?

Accepted Answer

A)  any direction as long as it is in the xy plane. 
B)  any direction as long as it is in the xz plane. 
C)  along the positive x axis. 
D)  along the positive y axis. 
E)  along the positive z axis.

Question 10

An electric field and a magnetic field are at right angles to each other and to the direction of a beam of electrons. There is no deflection of the beam when the magnitudes of the fields are 30 *104 V/m and 2.0 *10-3 T, respectively. The velocity of the electrons must be approximately

Accepted Answer

A)  0.60 km/s 
B)  6.7 * 10-8 m/s 
C)  2.3 * 1016 m/s 
D)  1.5 * 108 m/s 
E)  1.5* 10-8 m/s

Question 11

The rectangular aluminum strip in the figure is in a uniform magnetic field,  . The current I is flowing perpendicular to surface 1. Negative charges will accumulate on

Accepted Answer

A)  surface 1. 
B)  surface 2. 
C)  surface 3. 
D)  the surface opposite surface 2. 
E)  none of these surfaces.

Question 12

A circular, 20-turn coil has a radius of 5.0 cm. What is the magnitude of the magnetic moment of the coil when it carries a current of 2.5 A?

Accepted Answer

A)  1.5 A · m2  
B)  0.16 A · m2  
C)  2.0 *10-2 A · m2  
D)  0.39 A · m2  
E)  3.9 kA · m2

Question 13

A particle with charge q and mass m is moving with speed v in the +x direction enters a magnetic field of strength B pointing in the +y direction. The work done by the magnetic force on the particle as it travels one semi-circle is

Accepted Answer

A)   $\pi$mqvB 
B)   $\pi$mv2 
C)   $\pi$qvB 
D)  zero 
E)   $\pi$mv/qB

Question 14

A rectangle is bent on two sides at 90 $\degree$ so that one end lies along the xy plane while the other end lies along the xz plane. The length of each bent portion is illustrated on the Figure. A current I flows through the loop. The magnetic dipole of the rectangle is

Accepted Answer

A)   
B)   
C)   
D)   
E)  None of these is correct.

Question 15

An electron is traveling east with an instantaneous velocity of 3.3 * 105 m/s when it enters a uniform magnetic field of 0.25 T that points X degrees north of east. (Take east as to the right of the paper and north as towards the top of the paper, i.e. both in the plane of the paper.) If the magnitude of the force on the electron is 5.5*10-15 N, then calculate the angle X and whether the electron moves up out of or down into the plane of the page, or otherwise.

Accepted Answer

A)  26° and up out of the page 
B)  65° and down into the page 
C)  26° and down into the page 
D)  65° and up out of the page 
E)  65° and south in the plane of the paper

Question 16

A charged particle is moving horizontally westward with a velocity of 3.5* 106 m/s in a region where there is a magnetic field of magnitude 5.6 * 10-5 T directed vertically downward. The particle experiences a force of 7.8 * 10-16 N northward. What is the charge on the particle?

Accepted Answer

A)  +4.0 *10-18 C 
B)  -4.0 * 10-18 C 
C)  +4.9 * 10-5 C 
D)  -1.2 *10-14 C 
E)  +1.4 * 10-11 C

Question 17

A straight wire segment 3.0 m long makes an angle of 28º with a uniform magnetic field of 1.0 T. The magnitude of the force on the wire if it carries a current of 1.5 A is approximately

Accepted Answer

A)  2.1 N 
B)  4.0 N 
C)  1.4 N 
D)  0.70 N 
E)  4.7 N

Question 18

A circular 20-turn coil with a radius of 10 cm carries a current of 3 A. It lies in the xy plane in a uniform magnetic field  = 0.4 T  + 0.3 T  . The coil rotates so that its magnetic moment, $\mu$, is aligned with the magnetic field. The potential energy of the system when the coil's magnetic moment is aligned with the field is

Accepted Answer

A)  0.282 J 
B)  -0.461 J 
C)  0.461 J 
D)  -0.282 J 
E)  -0.564 J

Question 19

A beam of electrons is undeflected when it passes simultaneously through an electric field of 10 N/C perpendicular to its path and a magnetic field of 2 *10-4 T perpendicular both to its path and to the electric field. The speed of the electrons is approximately

Accepted Answer

A)  2 * 10-4 m/s 
B)  1 * 104 m/s 
C)  5 * 10-4 m/s 
D)  2* 104 m/s 
E)  5*104 m/s

Question 20

An electric field of 3.0 kV/m is perpendicular to a magnetic field of 0.20 T. An electron moving in a direction perpendicular to both  and  is not deflected if it has a velocity of

Accepted Answer

A)  6 km/s 
B)  9 km/s 
C)  12 km/s 
D)  15 km/s 
E)  6.7 m/s

Exam 6: The Magnetic Field

The region of space around a moving proton contains

The magnetic force on a charged particle

A current I flows in a wire that is oriented as shown. The vector representing the magnetic field that results in a maximum force on the wire is

A proton with a charge +e is moving with a speed v at 50º to the direction of a magnetic field . The component of the resulting force on the proton in the direction of is

The radius of curvature of the path of a charged particle moving perpendicular to a magnetic field is given by

A uniform magnetic field is parallel to and in the direction of the positive z axis. For an electron to enter this field and not be deflected by the field, the electron must be traveling in which direction?

An electric field and a magnetic field are at right angles to each other and to the direction of a beam of electrons. There is no deflection of the beam when the magnitudes of the fields are 30 10⁴ V/m and 2.0 10^-3 T, respectively. The velocity of the electrons must be approximately

The rectangular aluminum strip in the figure is in a uniform magnetic field, . The current I is flowing perpendicular to surface 1. Negative charges will accumulate on

A circular, 20-turn coil has a radius of 5.0 cm. What is the magnitude of the magnetic moment of the coil when it carries a current of 2.5 A?

A particle with charge q and mass m is moving with speed v in the +x direction enters a magnetic field of strength B pointing in the +y direction. The work done by the magnetic force on the particle as it travels one semi-circle is

A charged particle is moving horizontally westward with a velocity of 3.5* 10⁶ m/s in a region where there is a magnetic field of magnitude 5.6 * 10^-5 T directed vertically downward. The particle experiences a force of 7.8 * 10^-16 N northward. What is the charge on the particle?

A straight wire segment 3.0 m long makes an angle of 28º with a uniform magnetic field of 1.0 T. The magnitude of the force on the wire if it carries a current of 1.5 A is approximately

A beam of electrons is undeflected when it passes simultaneously through an electric field of 10 N/C perpendicular to its path and a magnetic field of 2 *10^-4 T perpendicular both to its path and to the electric field. The speed of the electrons is approximately

An electric field of 3.0 kV/m is perpendicular to a magnetic field of 0.20 T. An electron moving in a direction perpendicular to both and is not deflected if it has a velocity of

Exam 6: The Magnetic Field

The region of space around a moving proton contains

The magnetic force on a charged particle

A current I flows in a wire that is oriented as shown. The vector representing the magnetic field that results in a maximum force on the wire is

A proton with a charge +e is moving with a speed v at 50º to the direction of a magnetic field . The component of the resulting force on the proton in the direction of is

The radius of curvature of the path of a charged particle moving perpendicular to a magnetic field is given by

A uniform magnetic field is parallel to and in the direction of the positive z axis. For an electron to enter this field and not be deflected by the field, the electron must be traveling in which direction?

An electric field and a magnetic field are at right angles to each other and to the direction of a beam of electrons. There is no deflection of the beam when the magnitudes of the fields are 30 *104 V/m and 2.0 *10-3 T, respectively. The velocity of the electrons must be approximately

The rectangular aluminum strip in the figure is in a uniform magnetic field, . The current I is flowing perpendicular to surface 1. Negative charges will accumulate on

A circular, 20-turn coil has a radius of 5.0 cm. What is the magnitude of the magnetic moment of the coil when it carries a current of 2.5 A?

A particle with charge q and mass m is moving with speed v in the +x direction enters a magnetic field of strength B pointing in the +y direction. The work done by the magnetic force on the particle as it travels one semi-circle is

A rectangle is bent on two sides at 90 °\degree° so that one end lies along the xy plane while the other end lies along the xz plane. The length of each bent portion is illustrated on the Figure. A current I flows through the loop. The magnetic dipole of the rectangle is

A charged particle is moving horizontally westward with a velocity of 3.5* 106 m/s in a region where there is a magnetic field of magnitude 5.6 * 10-5 T directed vertically downward. The particle experiences a force of 7.8 * 10-16 N northward. What is the charge on the particle?

A straight wire segment 3.0 m long makes an angle of 28º with a uniform magnetic field of 1.0 T. The magnitude of the force on the wire if it carries a current of 1.5 A is approximately

A beam of electrons is undeflected when it passes simultaneously through an electric field of 10 N/C perpendicular to its path and a magnetic field of 2 *10-4 T perpendicular both to its path and to the electric field. The speed of the electrons is approximately

An electric field of 3.0 kV/m is perpendicular to a magnetic field of 0.20 T. An electron moving in a direction perpendicular to both and is not deflected if it has a velocity of

An electric field and a magnetic field are at right angles to each other and to the direction of a beam of electrons. There is no deflection of the beam when the magnitudes of the fields are 30 10⁴ V/m and 2.0 10^-3 T, respectively. The velocity of the electrons must be approximately

A charged particle is moving horizontally westward with a velocity of 3.5* 10⁶ m/s in a region where there is a magnetic field of magnitude 5.6 * 10^-5 T directed vertically downward. The particle experiences a force of 7.8 * 10^-16 N northward. What is the charge on the particle?

A beam of electrons is undeflected when it passes simultaneously through an electric field of 10 N/C perpendicular to its path and a magnetic field of 2 *10^-4 T perpendicular both to its path and to the electric field. The speed of the electrons is approximately