Question 1

Which is NOT one of the differences between a cyclotron and a synchrotron?

Accepted Answer

A) Orbits in a cyclotron are spirals, while in a synchrotron they are circles 
B) Conventional cyclotrons fail above energies of about 50 MeV because the proton speeds get too close to the speed of light, while synchrotrons are designed to accommodate all proton energies 
C) Large cyclotrons would require extremely large magnets, since they must cover all possible orbital radii, while synchrotrons only need a thin ring 
D) In general, synchrotrons are much smaller than cyclotrons 
E) Both cyclotrons and synchrotrons require electrical oscillators to accelerate the protons 
A) Orbits in a cyclotron are spirals, while in a synchrotron they are circles 
B) Conventional cyclotrons fail above energies of about 50 MeV because the proton speeds get too close to the speed of light, while synchrotrons are designed to accommodate all proton energies 
C) Large cyclotrons would require extremely large magnets, since they must cover all possible orbital radii, while synchrotrons only need a thin ring 
D) In general, synchrotrons are much smaller than cyclotrons 
E) Both cyclotrons and synchrotrons require electrical oscillators to accelerate the protons D

Question 2

You are facing a loop of wire which carries a clockwise current of 3.0 A and which surrounds an area of 5.8 x 10?2m2.The magnetic dipole moment of the loop is:

Accepted Answer

A) 3.0 A.m2, into the page 
B) 3.0 A.m2, out of the page 
C) 0.17 A.m2, into the page 
D) 0.17 A.m2, out of the page 
E) 0.17 A.m2, left to right 
A) 3.0 A.m2, into the page 
B) 3.0 A.m2, out of the page 
C) 0.17 A.m2, into the page 
D) 0.17 A.m2, out of the page 
E) 0.17 A.m2, left to right C

Question 3

In a certain mass spectrograph, an ion beam passes through a velocity filter consisting of mutually perpendicular fields   and   .The beam then enters a region of another magnetic field   perpendicular to the beam.The radius of curvature of the resulting ion beam is proportional to:

Accepted Answer

A) EB'/B 
B) EB/B' 
C) BB'/E 
D) B/EB' 
E) E/BB' 
A) EB'/B 
B) EB/B' 
C) BB'/E 
D) B/EB' 
E) E/BB' E

Question 4

The resonance condition in a cyclotron states that:

Accepted Answer

A) the time it takes the protons to make one cycle equals the natural frequency of the proton 
B) the protons oscillate on a vertical axis once per cycle 
C) the proton spin changes direction once per cycle 
D) the frequency of the proton orbits equals the frequency of the electrical oscillator 
E) the frequency of the proton orbits is an integer multiple of 60 Hz 
A) the time it takes the protons to make one cycle equals the natural frequency of the proton 
B) the protons oscillate on a vertical axis once per cycle 
C) the proton spin changes direction once per cycle 
D) the frequency of the proton orbits equals the frequency of the electrical oscillator 
E) the frequency of the proton orbits is an integer multiple of 60 Hz

Question 5

The magnetic force on a charged particle is in the direction of its velocity if:

Accepted Answer

A) it is moving in the direction of the field 
B) it is moving opposite to the direction of the field 
C) it is moving perpendicular to the field 
D) it is moving in some other direction 
E) never 
A) it is moving in the direction of the field 
B) it is moving opposite to the direction of the field 
C) it is moving perpendicular to the field 
D) it is moving in some other direction 
E) never

Question 6

A static magnetic field CANNOT:

Accepted Answer

A) exert a force on a charge 
B) accelerate a charge 
C) change the momentum of a charge 
D) change the kinetic energy of a charge 
E) exist 
A) exert a force on a charge 
B) accelerate a charge 
C) change the momentum of a charge 
D) change the kinetic energy of a charge 
E) exist

Question 7

A loop of wire carrying a current of 2.0 A is in the shape of a right triangle with two equal sides, each 15 cm long.A 0.7 T uniform magnetic field is parallel to the hypotenuse.The total magnetic force on the two equal sides has a magnitude of:

Accepted Answer

A) 0 N 
B) 0.21 N 
C) 0.30 N 
D) 0.41 N 
E) 0.51 N 
A) 0 N 
B) 0.21 N 
C) 0.30 N 
D) 0.41 N 
E) 0.51 N

Question 8

The diagram shows a straight wire carrying current i in a uniform magnetic field.The magnetic force on the wire is indicated by an arrow but the magnetic field is not shown.Of the following possibilities, the direction of the magnetic field is:

Accepted Answer

A) to the right 
B) opposite the direction of   
C) in the direction of   
D) into the page 
E) out of the page 
A) to the right 
B) opposite the direction of   
C) in the direction of   
D) into the page 
E) out of the page

Question 9

The direction of the magnetic field in a certain region of space is determined by firing a test charge into the region with its velocity in various directions in different trials.The field direction is:

Accepted Answer

A) one of the directions of the velocity when the magnetic force is zero 
B) the direction of the velocity when the magnetic force is a maximum 
C) the direction of the magnetic force 
D) perpendicular to the velocity when the magnetic force is zero 
E) none of the above 
A) one of the directions of the velocity when the magnetic force is zero 
B) the direction of the velocity when the magnetic force is a maximum 
C) the direction of the magnetic force 
D) perpendicular to the velocity when the magnetic force is zero 
E) none of the above

Question 10

The figure shows a uniform magnetic field   directed to the left and a wire carrying a current into the page.The magnetic force acting on the wire is:

Accepted Answer

A) toward the top of the page 
B) toward the bottom of the page 
C) toward the left 
D) toward the right 
E) zero 
A) toward the top of the page 
B) toward the bottom of the page 
C) toward the left 
D) toward the right 
E) zero

Question 11

An electron and a proton both each travel with equal speeds around circular orbits in the same uniform magnetic field, as shown in the diagram (not to scale).The field is into the page on the diagram.Because the electron is less massive than the proton and because the electron is negatively charged and the proton is positively charged:

Accepted Answer

A) the electron travels clockwise around the smaller circle and the proton travels counterclockwise around the larger circle. 
B) the electron travels counterclockwise around the smaller circle and the proton travels clockwise around the larger circle 
C) the electron travels clockwise around the larger circle and the proton travels counterclockwise around the smaller circle 
D) the electron travels counterclockwise around the larger circle and the proton travels clockwise around the smaller circle 
E) the electron travels counterclockwise around the smaller circle and the proton travels counterclockwise around the larger circle 
A) the electron travels clockwise around the smaller circle and the proton travels counterclockwise around the larger circle. 
B) the electron travels counterclockwise around the smaller circle and the proton travels clockwise around the larger circle 
C) the electron travels clockwise around the larger circle and the proton travels counterclockwise around the smaller circle 
D) the electron travels counterclockwise around the larger circle and the proton travels clockwise around the smaller circle 
E) the electron travels counterclockwise around the smaller circle and the proton travels counterclockwise around the larger circle

Question 12

The diagrams show five possible orientations of a magnetic dipole   in a uniform magnetic field   .For which of these does the magnetic torque on the dipole have the greatest magnitude?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 13

A uniform magnetic field is directed into the page.A charged particle, moving in the plane of the page, follows a clockwise spiral of decreasing radius as shown.A reasonable explanation is:

Accepted Answer

A) the charge is positive and slowing down 
B) the charge is negative and slowing down 
C) the charge is positive and speeding up 
D) the charge is negative and speeding up 
E) none of the above 
A) the charge is positive and slowing down 
B) the charge is negative and slowing down 
C) the charge is positive and speeding up 
D) the charge is negative and speeding up 
E) none of the above

Question 14

A charged particle is projected into a region of uniform, parallel,   and   fields.The force on the particle is:

Accepted Answer

A) zero 
B) at some angle < 90° with the field lines 
C) along the field lines 
D) perpendicular to the field lines 
E) unknown (need to know the sign of the charge) 
A) zero 
B) at some angle < 90° with the field lines 
C) along the field lines 
D) perpendicular to the field lines 
E) unknown (need to know the sign of the charge)

Question 15

A circular loop of wire with a radius of 20 cm lies in the xy plane and carries a current of 2 A, counterclockwise when viewed from a point on the positive z axis.Its magnetic dipole moment is:

Accepted Answer

A) 0.25 A.m2, in the positive z direction 
B) 0.25 A.m2, in the negative z direction 
C) 2.5 A.m2, in the positive z direction 
D) 2.5 A.m2, in the negative z direction 
E) 0.25 A.m2, in the xy plane 
A) 0.25 A.m2, in the positive z direction 
B) 0.25 A.m2, in the negative z direction 
C) 2.5 A.m2, in the positive z direction 
D) 2.5 A.m2, in the negative z direction 
E) 0.25 A.m2, in the xy plane

Question 16

An electron is launched with velocity   in a uniform magnetic field   .The angle $\theta$between   and   is between 0 and 90o.As a result, the electron follows a helical path.The pitch of the helix is:

Accepted Answer

A) the angle the helix makes with the magnetic field 
B) the angle the helix makes with the electron's velocity vector 
C) the radius of the circular motion 
D) the distance between adjacent turns of the helix 
E) the time it takes the electron to move from one turn of the helix to the next 
A) the angle the helix makes with the magnetic field 
B) the angle the helix makes with the electron's velocity vector 
C) the radius of the circular motion 
D) the distance between adjacent turns of the helix 
E) the time it takes the electron to move from one turn of the helix to the next

Question 17

A loop of wire carrying a current of 2.0 A is in the shape of a right triangle with two equal sides, each 15 cm long.A 0.7 T uniform magnetic field is in the plane of the triangle and is perpendicular to the hypotenuse.The resultant magnetic force on the two equal sides has a magnitude of:

Accepted Answer

A) 0 N 
B) 0.21 N 
C) 0.30 N 
D) 0.41 N 
E) 0.51 N 
A) 0 N 
B) 0.21 N 
C) 0.30 N 
D) 0.41 N 
E) 0.51 N

Question 18

A magnetic field exerts a force on a charged particle:

Accepted Answer

A) always 
B) never 
C) if the particle is moving across the field lines 
D) if the particle is moving along the field lines 
E) if the particle is at rest 
A) always 
B) never 
C) if the particle is moving across the field lines 
D) if the particle is moving along the field lines 
E) if the particle is at rest

Question 19

A loop of current-carrying wire has a magnetic dipole moment of 5.0 * 10-4 A.m2.The moment initially is aligned with a 0.50-T magnetic field.To rotate the loop so its dipole moment is perpendicular to the field and hold it in that orientation, you must do work of:

Accepted Answer

A) 0 J 
B) 2.5 * 10-4 J 
C) -2.5* 10-4 J 
D) 1.0* 10-3 J 
E) -1.0 *10-3 J 
A) 0 J 
B) 2.5 * 10-4 J 
C) -2.5* 10-4 J 
D) 1.0* 10-3 J 
E) -1.0 *10-3 J

Question 20

A cyclotron operates with a given magnetic field and at a given frequency.If R denotes the radius of the final orbit, the final particle energy is proportional to:

Accepted Answer

A) 1/R 
B) R 
C) R2 
D) R3 
E) R4 
A) 1/R 
B) R 
C) R2 
D) R3 
E) R4

Exam 28: Magnetic Fields

Which is NOT one of the differences between a cyclotron and a synchrotron?

You are facing a loop of wire which carries a clockwise current of 3.0 A and which surrounds an area of 5.8 x 10?2m2.The magnetic dipole moment of the loop is:

In a certain mass spectrograph, an ion beam passes through a velocity filter consisting of mutually perpendicular fields and .The beam then enters a region of another magnetic field perpendicular to the beam.The radius of curvature of the resulting ion beam is proportional to:

The resonance condition in a cyclotron states that:

The magnetic force on a charged particle is in the direction of its velocity if:

A static magnetic field CANNOT:

A loop of wire carrying a current of 2.0 A is in the shape of a right triangle with two equal sides, each 15 cm long.A 0.7 T uniform magnetic field is parallel to the hypotenuse.The total magnetic force on the two equal sides has a magnitude of:

The diagram shows a straight wire carrying current i in a uniform magnetic field.The magnetic force on the wire is indicated by an arrow but the magnetic field is not shown.Of the following possibilities, the direction of the magnetic field is:

The direction of the magnetic field in a certain region of space is determined by firing a test charge into the region with its velocity in various directions in different trials.The field direction is:

The figure shows a uniform magnetic field directed to the left and a wire carrying a current into the page.The magnetic force acting on the wire is:

The diagrams show five possible orientations of a magnetic dipole in a uniform magnetic field .For which of these does the magnetic torque on the dipole have the greatest magnitude?

A uniform magnetic field is directed into the page.A charged particle, moving in the plane of the page, follows a clockwise spiral of decreasing radius as shown.A reasonable explanation is:

A charged particle is projected into a region of uniform, parallel, and fields.The force on the particle is:

A circular loop of wire with a radius of 20 cm lies in the xy plane and carries a current of 2 A, counterclockwise when viewed from a point on the positive z axis.Its magnetic dipole moment is:

An electron is launched with velocity in a uniform magnetic field .The angle θ\thetaθ between and is between 0 and 90o.As a result, the electron follows a helical path.The pitch of the helix is:

A loop of wire carrying a current of 2.0 A is in the shape of a right triangle with two equal sides, each 15 cm long.A 0.7 T uniform magnetic field is in the plane of the triangle and is perpendicular to the hypotenuse.The resultant magnetic force on the two equal sides has a magnitude of:

A magnetic field exerts a force on a charged particle:

A loop of current-carrying wire has a magnetic dipole moment of 5.0 * 10-4 A.m2.The moment initially is aligned with a 0.50-T magnetic field.To rotate the loop so its dipole moment is perpendicular to the field and hold it in that orientation, you must do work of:

A cyclotron operates with a given magnetic field and at a given frequency.If R denotes the radius of the final orbit, the final particle energy is proportional to:

Measurement

Motion Along a Straight Line

Vectors

Motion in Two and Three Dimensions

Force and Motion

Force and Motion

Kinetic Energy and Work

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

Waves

Waves

Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Coulombs Law

Electric Fields

Gauss Law

Electric Potential

Capacitance

Current and Resistance

Circuits

Magnetic Fields Due to Currents

Induction and Inductance

Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference 1

Diffraction

Relativity

Photons and Matter Waves

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

Filters

You are facing a loop of wire which carries a clockwise current of 3.0 A and which surrounds an area of 5.8 x 10^?2m².The magnetic dipole moment of the loop is:

A loop of current-carrying wire has a magnetic dipole moment of 5.0 * 10^-4 A.m².The moment initially is aligned with a 0.50-T magnetic field.To rotate the loop so its dipole moment is perpendicular to the field and hold it in that orientation, you must do work of: