Ch.210.1,2

Question 1

1. Which one of the following statements concerning permanent magnets is false?

Answer 1

A) The north pole of a permanent magnet is attracted to a south pole.
B) All permanent magnets are surrounded by a magnetic field.
C) The direction of a magnetic field is indicated by the north pole of a compass.
D) Magnetic field lines outside a permanent magnet originate from the north pole and end on the south pole.
E) ——- When a permanent magnet is cut in half, one piece will be a north pole and one piece will be a south pole.

Question 2

2. Which combination of units can be used to express the magnetic field?

Answer 2

A)  kg × m2/C
B)  kg × s/C2
C)  N × m2/C
D) ------- kg/(C × s) 
E)  kg × m/(C × s2)

Question 3

3. Which one of the following statements concerning the magnetic force on a charged particle in a magnetic field is true?

Answer 3

A) The magnetic force is a maximum if the particle is stationary.
B) The magnetic force is zero if the particle moves perpendicular to the field.
C) The magnetic force is a maximum if the particle moves parallel to the field.
D) The magnetic force acts in the direction of motion for a positively charged particle.
E) ——- The magnetic force depends on the component of the particle’s velocity that is perpendicular to the field

Question 4

4. Complete the following statement: The magnitude of the magnetic force that acts on a charged particle in a magnetic field is independent of

Answer 4

A) ——-the sign of the charge.
B) the magnitude of the charge.
C) the magnitude of the magnetic field.
D) the direction of motion of the particle.
E) the velocity components of the particle.

Question 5

5. A charged particle is moving in a uniform, constant magnetic field. Which one of the following statements concerning the magnetic force exerted on the particle is false?

Answer 5

A) The magnetic force does no work on the particle.
B) ——- The magnetic force increases the speed of the particle.
C) The magnetic force changes the velocity of the particle.
D) The magnetic force can act only on a particle in motion.
E) The magnetic force does not change the kinetic energy of the particle.

Question 6

6. A proton traveling due west in a region that contains only a magnetic field experiences a vertically upward force (away from the surface of the earth). What is the direction of the magnetic field?

Answer 6

A)  north
B)  east
C) ----- south
D)  west
E)  down

Question 7

7. A charged particle is launched with a velocity of 5.2 × 104 m/s at an angle of 35° with respect to a 0.0045-T magnetic field. If the magnetic field exerts a force of 0.0026 N on the particle, determine the magnitude of the charge on the particle.

Answer 7

A)  11 µC
B)  15 µC
C) ----- 19 µC
D)  23 µC
E)  27 µC

Question 8

8. Which one of the following statements best explains why a constant magnetic field can do no work on a moving charged particle?

Answer 8

A) The magnetic field is conservative.
B) The magnetic force is a velocity dependent force.
C) The magnetic field is a vector and work is a scalar quantity.
D) —– The magnetic force is always perpendicular to the velocity of the particle.
E) The electric field associated with the particle cancels the effect of the magnetic field on the particle.

Question 9

9. An electron traveling due north enters a region that contains a uniform magnetic field that points due east. In which direction will the electron be deflected?

Answer 9

A)  east
B)  west
C)  up
D) ----- down
E)  south

Question 10

10. Two electrons are located in a region of space where the magnetic field is zero. Electron A is at rest; and electron B is moving westward with a constant velocity. A non-zero magnetic field directed eastward is then applied to the region. In what direction, if any, will each electron be moving after the field is applied?

Answer 10

Electron A: at rest

Electron B: westward

Question 11

11. An electron is moving with a speed of 3.5 × 105 m/s when it encounters a magnetic field of 0.60 T. The direction of the magnetic field makes an angle of 60.0° with respect to the velocity of the electron. What is the magnitude of the magnetic force on the electron?

Answer 11

A)  4.9 × 10–13 N
B)  3.2 × 10–13 N
C)  1.7 × 10–13 N
D)  3.4 × 10–14 N
E) ----- 2.9 × 10–14 N

Question 12

12. An electron traveling due south enters a region that contains both a magnetic field and an electric field.
    The electric field lines point due west. It is observed that the electron continues to travel in a straight line due south. In which direction must the magnetic field lines point?

Answer 12

A)  up
B) ----- down
C)  east
D)  west
E)  south

Question 13

13. An proton travels through a region of space with no acceleration. Which one of the following statements is the best conclusion?

Answer 13

A) Both E and B must be zero in that region.
B) E must be zero, but B might be non-zero in that region.
C) —– E and B might both be non-zero, but they must be mutually perpendicular.
D) B must be zero, but E might be non-zero in that region.
E) E and B might both be non-zero, but they must point in opposite directions.

Question 14

14. A proton is traveling south as it enters a region that contains a magnetic field. The proton is deflected downward toward the earth. What is the direction of the magnetic field?

Answer 14

A)  downward,  toward the earth
B) ----- west
C)  north
D)  east
E)  south

Question 15

15. A particle with a mass of 6.64 × 10–27 kg and a charge of +3.20 × 10–19 C is accelerated from rest through a potential difference of 2.45 × 106 V. The particle then enters a uniform 1.60-T magnetic field. If the particle’s velocity is perpendicular to the magnetic field at all times, what is the magnitude of the magnetic force exerted on the particle?

Answer 15

A)  zero newtons
B)  1.14 × 10–10 N
C)  6.55 × 10–10 N
D)  4.09 × 10–11 N
E) ----- 7.87 × 10–12 N

Question 16

16. An electron traveling horizontally enters a region where a uniform magnetic field is directed into the plane of the paper as shown. Which one of the following phrases most accurately describes the motion of the electron once it has entered the field?

Answer 16

A)  upward and parabolic
B)  upward and circular
C) ----- downward and circular
D)  upward, along a straight line
E)  downward and parabolic

Question 17

17. An electron enters a region that contains a magnetic field directed into the page as shown. The velocity vector of the electron makes an angle of 30° with the +y axis. What is the direction of the magnetic force on the electron when it enters the field?

Answer 17

A) up, out of the page
B) —– at an angle of 30° below the positive x axis
C) at an angle of 30° above the positive x axis
D) at an angle of 60° below the positive x axis
E) at an angle of 60° above the positive x axis

Question 18

18. Two particles move through a uniform magnetic field that is directed out of the plane of the page. The figure shows the paths taken by the two particles as they move through the field. The particles are not subject to any other forces or fields. Which one of the following statements concerning these particles is true?

Answer 18

A) The particles may both be neutral.
B) Particle 1 is positively charged; 2 is negative.
C) Particle 1 is positively charged; 2 is positive.
D) —– Particle 1 is negatively charged; 2 is negative.
E) Particle 1 is negatively charged; 2 is positive.

Question 19

19. A mass spectrometer is used to separate two isotopes of uranium with masses m1 and m2 where m2 > m1. The two types of uranium atom exit an ion source S with the same charge of +e and are accelerated through a potential difference V. The charged atoms then enter a constant, uniform magnetic field B as shown. If r1 = 0.5049 m and r2 = 0.5081 m, what is the value of the ratio m1/m2?

Answer 19

A)  0.9984
B)  0.9937
C) ----- 0.9874
D)  0.9812
E)  0.9749

Question 20

20. Two charged particles of equal mass are traveling in circular orbits in a region of uniform, constant magnetic field as shown. The particles are observed to move in circular paths of radii R1 and R2 with speeds v1 and v2, respectively.

As the figure shows, the path of particle 2 has a smaller radius than that of particle 1. Which one of the following statements about this system is false?

Answer 20

A) —– |v1/Q1| < |v2/Q2|
B) Particle 2 carries a positive charge.
C) Particle 1 carries a negative charge.
D) Neither particle gains energy from the magnetic field.
E) The particle velocities have no components parallel to the magnetic field.