Physics chapter 22

23) An electron, moving west, enters a magnetic field of a certain strength. Because of this field the electron curves upward. What is the direction of the magnetic field? A) towards the north B) towards the south C) upward D) downward E) towards the west

A

33) A rectangular coil, with corners labeled ABCD, of length L and width w is placed in a magnetic field B as shown in Figure 22-3. If there is a current I flowing through this coil, what is the direction of the force acting on section AB of this coil? A) perpendicular to and into the page B) perpendicular to and out of the page C) in the direction of the magnetic field D) in the opposite direction of the magnetic field E) none

A

41) Two long, parallel wires carry currents of different magnitudes. If the amount of current in each wire is doubled, what happens to the magnitude of the force between the wires? A) It is quadrupled. B) It is doubled. C) It is tripled. D) It stays the same. E) It is reduced by a factor of 2.

A

42) When you double the number of windings in a solenoid keeping all other parameters (radius, length and current) fixed, the magnetic field at the center of the solenoid will A) double. B) triple. C) quadruple. D) be reduced to one-fourth as much. E) be reduced to half as much.

A

paramagnetism

A material that has no magnetic field unless an external magnetic field is applied to it. In this case, it develops a magnetization is the direction of the external field.

ferromagnetism

A material that produces a magnetic field even in the absence of an external magnetic field. Permanent magnets are constructed of this material

20) An electron moving along the +x-axis enters a magnetic field. If the electron experiences a magnetic deflection in the -y direction, what is the direction of the magnetic field in this region? A) along the +z-axis B) along the -z-axis C) along the -x-axis D) along the +y-axis E) along the -y-axis

B

31) A rectangular coil, with corners labeled ABCD, of length L and width w is placed in a magnetic field B as shown in Figure 22-3. If there is a current I flowing through this coil, what is the force acting on section BC of this coil? A) ILB/2 B) 0 N C) ILB sinθ D) ILB cos θ E) ILB

B

34) A rectangular coil, with corners labeled ABCD, of length L and width w is placed in a magnetic field B as shown in Figure 22-3. If there is a current I flowing through this coil, what is the direction of the force acting on section CD of this coil? A) perpendicular to and into the page B) perpendicular to and out of the page C) in the direction of the magnetic field D) in the opposite direction of the magnetic field E) none

B

38) A single current-carrying circular loop of radius R is placed next to a long, straight wire, as shown in the sketch in Figure 22-6. The current in the wire points to the right and is of magnitude I. In which direction must current flow in the loop to produce zero magnetic field at its center? A) counterclockwise B) clockwise C) It is indifferent if clockwise or counterclockwise. D) The current in the loop should be zero A.

B

40) Two long, parallel wires carry currents of different magnitudes. If the current in one of the wires is doubled and the current in the other wire is halved, what happens to the magnitude of the force between these two wires? A) It is doubled. B) It stays the same. C) It is tripled. D) It is quadrupled. E) It is reduced by a factor of 2.

B

18) Which of the following statements is correct? A) Earth's geographic north pole is the north pole of the Earth's magnetic field. B) Earth's geographic south pole is the south pole of the Earth's magnetic field. C) The north pole of a magnet points towards the Earth's geographic north pole. D) The north pole of a magnet points towards the Earth's geographic south pole. E) None of the above statements is correct..

C

22) A proton, moving north, enters a magnetic field of a certain strength. Because of this field the proton curves downward. What is the direction of the magnetic field? A) downward B) upward C) towards the east D) towards the west E) towards the north

C

24) A proton, moving west, enters a magnetic field of a certain strength. Because of this magnetic field the proton curves upward. What is the direction of this magnetic field? A) towards the west B) towards the east C) towards the south D) towards the north E) downward

C

28) A charged particle moving with a certain velocity along the +x-axis enters a magnetic field pointing toward the +z-axis. Because of an electric field along the +y-axis the charge particle continues to move along the +x-axis. What is the sign of this particle? A) positive B) negative C) The particle could be either positive or negative. D) None of the other choices is correct.

C

32) A rectangular coil, with corners labeled ABCD, of length L and width w is placed in a magnetic field B as shown in Figure 22-3. If there is a current I flowing through this coil, what is the force acting on section AB of this coil?

C

35) A wire is carrying current vertically downward. What is the direction of the force due to Earth's magnetic field on the wire? A) horizontally towards the north B) horizontally towards the south C) horizontally towards the east D) horizontally towards the west E) vertically upward

C

36) When the switch is closed in the circuit shown in the sketch in Figure 22-4, the wire between the poles of the horseshoe magnet deflects upward. From this you can conclude that the left end of the magnet is A) not contributing to the wire's deflection. B) a north magnetic pole. C) a south magnetic pole. D) a magnetic monopole. E) a magnetic dipole.

C

21) An electron, moving south, enters a magnetic field of certain strength. Because of this field the electron curves upward. What is the direction of the magnetic field? A) downward B) towards the east C) upward D) towards the west E) towards the north

D

25) A proton moving in a region of a space does not experience any acceleration in the direction of motion. Which of the following statements is correct with respect to this situation? A) The electric and magnetic fields must be perpendicular to each other in that region. B) The electric and magnetic fields must be parallel to each other in that region. C) Both electric and magnetic fields must be zero in that region. D) The electric field must be zero but not the magnetic field in that region. E) The magnetic field must be zero but not the electric field in that region.

D

30) A rectangular coil, with corners labeled ABCD, of length L and width w is placed in a magnetic field B as shown in Figure 22-2. If there is no current flowing through the coil, what is the force acting on section AB of the coil? A) ILB sinθ B) ILB cos θ C) ILB D) 0 N E) None of the other answers is correct.

D

39) 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 magnetic field due to this wire? 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

D

19) A +2-μC charge is at rest in a magnetic field of 2 T pointing along the +x-axis. What is the force acting on this charge in the magnetic field? A) -4 μN B) +4 μN C) -2 μN D) +2 μN E) 0 N

E

26) Three particles travel through a region of space where the magnetic field is out of the page, as shown in Figure 22-1. The electric charge of each of the three particles is, respectively, A) 1 is neutral, 2 is negative, and 3 is positive. B) 1 is neutral, 2 is positive, and 3 is negative. C) 1 is positive, 2 is neutral, and 3 is negative. D) 1 is positive, 2 is negative, and 3 is neutral. E) 1 is negative, 2 is neutral, and 3 is positive.

E

27) An electron moving in the positive y direction, at right angles to a magnetic field, experiences a magnetic force in the negative x direction. What is the direction of the magnetic field? A) It is in the negative x direction. B) It is in the positive x direction. C) It is in the positive y direction. D) It is in the negative z direction. E) It is in the positive z direction.

E

29) A proton is to orbit Earth at the equator using Earth's magnetic field to supply part of the necessary centripetal force. In what direction should the proton move? A) upward B) northward C) southward D) eastward E) westward

E

37) A metal bar of mass m and length L is suspended from two conducting wires, as shown in the sketch in Figure 22-5. A uniform magnetic field points vertically downward. Choose the expression that best describes the condition satisfied by the angle θ that the suspending wires make with the vertical when the bar carries a current I. A) tan (theta) = ml/BgL B) tan (theta) = mg/BIL C) tan (theta) = Bg/mIL D) tan (theta) = mIL/Bg E) tan (theta) = BIL/mg

E

A wire carrying a current that placed in a magnetic field will experience a maximum force if the angle between the direction of the current and the direction of the magnetic field is 60°.

FALSE

If two identical wires carrying a certain current in the same direction are placed parallel to each other, they will experience a force of repulsion.

FALSE

The field near a long straight wire carrying a current is inversely proportional to the current flowing through the wire.

FALSE

The magnetic field near a current carrying wire is directly proportional to the distance from the wire.

FALSE

The magnitude of the magnetic field inside a solenoid is inversely proportional to the current flowing through the solenoid.

FALSE

4) At a given location the direction of the magnetic field is the direction that the north pole of a compass points when placed at that location.

TRUE

A charged particle traveling opposite to a magnetic field does not experience a magnetic force.

TRUE

A current carrying wire placed in a magnetic field perpendicular to the wire experiences a maximum force.

TRUE

A rectangular coil carrying a current in a magnetic field will experience a net torque that will cause the coil to rotate in that field, if the field is not along the coil axis.

TRUE

An electric field makes a charged particle accelerate but a magnetic field takes it around in a circle.

TRUE

For any displacement of a charged particle, the work done by the magnetic force on the charged particle moving in a magnetic field is zero J.

TRUE

Magnetic field lines can never cross one another.

TRUE

The magnetic field unlike the electric field is continuous.

TRUE

The magnetic force on a circular loop of wire of radius r carrying current I around it is zero N.

TRUE

diamagnetism

the effect of the production by a material of a magnetic field in the opposite direction to an external magnetic field that is applied to it. All materials show at least a small bit of this effect