Question 1

A charged particle moving within a static magnetic field

Accepted Answer

A) will always experience a magnetic force,regardless of its direction of motion. 
B) may experience a magnetic force that will cause its speed to change. 
C) may experience a magnetic force,but its speed will not change. 
D) None of the above statements are true. 
A) will always experience a magnetic force,regardless of its direction of motion. 
B) may experience a magnetic force that will cause its speed to change. 
C) may experience a magnetic force,but its speed will not change. 
D) None of the above statements are true.

Question 2

-A solenoid of length 18 cm consists of a wire wrapped tightly around a wooden core.The magnetic field strength is 2.0 T inside the solenoid.If the solenoid is stretched to 29 cm by applying a force to it,what does the magnetic field become?

Accepted Answer

A) 1.2 T 
B) 3.2 T 
C) 15 T 
D) 2.0 T 
A) 1.2 T 
B) 3.2 T 
C) 15 T 
D) 2.0 T

Question 3

A straight bar magnet is initially 4 cm long,with the north pole on the right and the south pole on the left.If you cut the magnet in half,the right half will

Accepted Answer

A) only contain a north pole. 
B) still contain a north pole on the right and a new south pole on the left. 
C) only contain a south pole. 
A) only contain a north pole. 
B) still contain a north pole on the right and a new south pole on the left. 
C) only contain a south pole.

Question 4

If the magnetic field strength is 20 μT at a distance of 3.0 cm from a long,straight,very thin current-carrying wire,the field will be 5 μT 12 cm away from the wire.

Accepted Answer

A) True 
 B)False

Question 5

A compass is placed close to a stationary charge.If the charge remains stationary,the compass will not deflect,but if the charge moves,the compass will deflect.

Accepted Answer

A) True 
 B)False

Question 6

A mass spectrograph is operated with deuterons, which have a charge of +e and a mass of 
3.34 × 10S1U1P1-27S1S1P0 kg. Deuterons emerge from the source, which is grounded with negligible velocity. The velocity of the deuterons as they pass through the accelerator grid is 8.0 × 10S1U1P15S1S1P0 m/s. A uniform magnetic field of magnitude B = 0.20 T, directed out of the plane, is present at the right of the grid.
-In the figure,the deuterons are in circular orbit in the magnetic field.The radius of the orbit and the initial sense of deflection are closest to:

Accepted Answer

A) 60 mm,upward 
B) 70 mm,upward 
C) 60 mm,downward 
D) 70 mm,downward 
E) 80 mm,downward 
A) 60 mm,upward 
B) 70 mm,upward 
C) 60 mm,downward 
D) 70 mm,downward 
E) 80 mm,downward

Question 7

A charged particle of mass 0.0040 kg is subjected to a 4.0 T magnetic field that acts at a right angle to its motion.If the particle moves in a circle of radius 0.10 m at a speed of 2.0 m/s,what is the magnitude of the charge on the particle?

Accepted Answer

A) 0.020 C 
B) 50 C 
C) 0.00040 C 
D) 2500 C 
A) 0.020 C 
B) 50 C 
C) 0.00040 C 
D) 2500 C

Question 8

Two long,parallel bars carry equal currents in opposite directions.The magnetic fields due to these two currents cancel each other midway between the two bars.

Accepted Answer

A) True 
 B)False

Question 9

A small plastic ball has an excess negative charge on it.If a magnet is placed close to this ball,it will either attract or repel the ball,depending upon which pole is closer to the ball.

Accepted Answer

A) True 
 B)False

Question 10

If a magnetic compass is placed between the plates of a fully charged capacitor,the compass will align itself along the electric field lines.

Accepted Answer

A) True 
 B)False

Question 11

A very long wire generates a magnetic field of 0.0050 × 10-4 T at a distance of 3.0 mm.What is the magnitude of the current?

Accepted Answer

A) 7.5 mA 
B) 1.7 mA 
C) 3300 mA 
D) 24,000 mA 
A) 7.5 mA 
B) 1.7 mA 
C) 3300 mA 
D) 24,000 mA

Question 12

Alpha particles (charge = +2e,mass = 6.68 × 10-27 kg)are accelerated in a cyclotron to a final orbit radius of 0.30 m.The magnetic field in the cyclotron is 0.80 T.The period of circular motion of the alpha particles is closest to:

Accepted Answer

A) 0.16 μs 
B) 0.25 μs 
C) 0.33 μs 
D) 0.40 μs 
E) 0.49 μs 
A) 0.16 μs 
B) 0.25 μs 
C) 0.33 μs 
D) 0.40 μs 
E) 0.49 μs

Question 13

Inside of an ideal solenoid,the closer you get to the metal windings,the stronger the magnetic field gets.

Accepted Answer

A) True 
 B)False

Question 14

-A solenoid is wound with 470 turns on a form 4 cm in diameter and 50 cm long.The windings carry a current in the sense that is shown.The current produces a magnetic field,of magnitude 4.1 mT,at the center of the solenoid.In the figure,the current in the solenoid windings is closest to:

Accepted Answer

A) 3.5 A 
B) 3.0 A 
C) 2.6 A 
D) 4.3 A 
E) 3.9 A 
A) 3.5 A 
B) 3.0 A 
C) 2.6 A 
D) 4.3 A 
E) 3.9 A

Question 15

A circular coil of wire of 200 turns and diameter 6 cm carries a current of 7 A.It is placed in a magnetic field of 0.90 T with the plane of the coil making an angle of 30° with the magnetic field.What is the torque on the coil?

Accepted Answer

A) 3.1 N ∙ m 
B) 1.8 N ∙ m 
C) 5.9 N ∙ m 
D) 8.2 N ∙ m 
E) 1.5 N ∙ m 
A) 3.1 N ∙ m 
B) 1.8 N ∙ m 
C) 5.9 N ∙ m 
D) 8.2 N ∙ m 
E) 1.5 N ∙ m

Question 16

A ring with a clockwise current (as seen from above the ring)is situated with its center directly above another ring,which has a counterclockwise current,as shown in the figure.In what direction is the net magnetic force exerted on the top ring?

Accepted Answer

A) upward 
B) downward 
C) The net force is zero. 
D) Impossible to determine 
A) upward 
B) downward 
C) The net force is zero. 
D) Impossible to determine

Question 17

Which of the following is an accurate statement?

Accepted Answer

A) Magnetic field lines have as their sources north and south poles. 
B) A magnetic field line is,by definition,tangent to the direction of the magnetic force on a moving charge at a given point in space. 
C) The magnetic force on a moving charge does not change its energy. 
D) The magnetic force on a current-carrying wire is greatest when the wire is parallel to the magnetic field. 
E) A current-carrying loop of wire tends to line up with its plane parallel to an external magnetic field in which it is positioned. 
A) Magnetic field lines have as their sources north and south poles. 
B) A magnetic field line is,by definition,tangent to the direction of the magnetic force on a moving charge at a given point in space. 
C) The magnetic force on a moving charge does not change its energy. 
D) The magnetic force on a current-carrying wire is greatest when the wire is parallel to the magnetic field. 
E) A current-carrying loop of wire tends to line up with its plane parallel to an external magnetic field in which it is positioned.

Question 18

A uniform magnetic field of magnitude 0.80 T in the negative z-direction is present in a region of space.A uniform electric field is also present.In the figure,the electric field is set at 20,800 V/m in the positive y-direction.An electron is projected with an initial velocity vo = 2.6 × 104 m/s.in the positive x-direction.The y-component of the initial force on the electron is closest to:

Accepted Answer

A) - 7 × 10-15 N 
B) + 7 × 10-15 N 
C) - 3 × 10-15 N 
D) + 3 × 10-15 N 
E) zero 
A) - 7 × 10-15 N 
B) + 7 × 10-15 N 
C) - 3 × 10-15 N 
D) + 3 × 10-15 N 
E) zero

Question 19

If you were to cut a small permanent bar magnet in half,

Accepted Answer

A) one piece would be a magnetic north pole and the other piece would be a south pole. 
B) neither piece would be magnetic. 
C) each piece would in itself be a smaller bar magnet with both north and south poles. 
D) None of these statements is true. 
A) one piece would be a magnetic north pole and the other piece would be a south pole. 
B) neither piece would be magnetic. 
C) each piece would in itself be a smaller bar magnet with both north and south poles. 
D) None of these statements is true.

Question 20

Consider a solenoid of length L,N windings,and radius b (L is much longer than b).A current I is flowing through the wire.If the length of the solenoid became twice as long (2L),and all other quantities remained the same,the magnetic field inside the solenoid would

Accepted Answer

A) stay the same. 
B) become twice as strong as initially. 
C) become half as strong as initially. 
A) stay the same. 
B) become twice as strong as initially. 
C) become half as strong as initially.

Exam 24: Magnetic Fields and Forces

A charged particle moving within a static magnetic field

-A solenoid of length 18 cm consists of a wire wrapped tightly around a wooden core.The magnetic field strength is 2.0 T inside the solenoid.If the solenoid is stretched to 29 cm by applying a force to it,what does the magnetic field become?

A straight bar magnet is initially 4 cm long,with the north pole on the right and the south pole on the left.If you cut the magnet in half,the right half will

If the magnetic field strength is 20 μT at a distance of 3.0 cm from a long,straight,very thin current-carrying wire,the field will be 5 μT 12 cm away from the wire.

A compass is placed close to a stationary charge.If the charge remains stationary,the compass will not deflect,but if the charge moves,the compass will deflect.

A charged particle of mass 0.0040 kg is subjected to a 4.0 T magnetic field that acts at a right angle to its motion.If the particle moves in a circle of radius 0.10 m at a speed of 2.0 m/s,what is the magnitude of the charge on the particle?

Two long,parallel bars carry equal currents in opposite directions.The magnetic fields due to these two currents cancel each other midway between the two bars.

A small plastic ball has an excess negative charge on it.If a magnet is placed close to this ball,it will either attract or repel the ball,depending upon which pole is closer to the ball.

If a magnetic compass is placed between the plates of a fully charged capacitor,the compass will align itself along the electric field lines.

A very long wire generates a magnetic field of 0.0050 × 10-4 T at a distance of 3.0 mm.What is the magnitude of the current?

Alpha particles (charge = +2e,mass = 6.68 × 10-27 kg)are accelerated in a cyclotron to a final orbit radius of 0.30 m.The magnetic field in the cyclotron is 0.80 T.The period of circular motion of the alpha particles is closest to:

Inside of an ideal solenoid,the closer you get to the metal windings,the stronger the magnetic field gets.

-A solenoid is wound with 470 turns on a form 4 cm in diameter and 50 cm long.The windings carry a current in the sense that is shown.The current produces a magnetic field,of magnitude 4.1 mT,at the center of the solenoid.In the figure,the current in the solenoid windings is closest to:

A circular coil of wire of 200 turns and diameter 6 cm carries a current of 7 A.It is placed in a magnetic field of 0.90 T with the plane of the coil making an angle of 30° with the magnetic field.What is the torque on the coil?

A ring with a clockwise current (as seen from above the ring)is situated with its center directly above another ring,which has a counterclockwise current,as shown in the figure.In what direction is the net magnetic force exerted on the top ring?

Which of the following is an accurate statement?

If you were to cut a small permanent bar magnet in half,

Consider a solenoid of length L,N windings,and radius b (L is much longer than b).A current I is flowing through the wire.If the length of the solenoid became twice as long (2L),and all other quantities remained the same,the magnetic field inside the solenoid would

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A very long wire generates a magnetic field of 0.0050 × 10^-4T at a distance of 3.0 mm.What is the magnitude of the current?

Alpha particles (charge = +2e,mass = 6.68 × 10^-27 kg)are accelerated in a cyclotron to a final orbit radius of 0.30 m.The magnetic field in the cyclotron is 0.80 T.The period of circular motion of the alpha particles is closest to: