PHY2049 - GENERAL PHYSICS II
PRACTICE QUIZ 26

Below you will find a set of 5 conceptual and numerical revision questions selected randomly from lots of questions I have put together covering the material in Chapter 26, "The Magnetic Field". This includes questions on the force exerted by a magnetic field, motion of a charge in a magnetic field and torques on current loops and magnets. When you have finished the quiz, click on the "Submit Quiz" button at the bottom and within seconds it will be automatically graded and the results returned to you!

To select a new set of questions click on the "Reload" or "Refresh" button on your browser. You may find some of the questions duplicated but that's the nature of a random selection. Try it a few times ... it's not fattening and you may learn something!

Many thanks to Mark Wood for producing the quiz-maker code.


Q1: 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 +yaxis. What is the direction of the magnetic force on the electron when it enters the field?



up, out of the page
at an angle of 30° below the positive x axis
at an angle of 30° above the positive x axis
at an angle of 60° below the positive x axis
at an angle of 60° above the positive x axis


Q2: A positively charged particle moves with velocity v along the x axis and through a uniform magnetic field B directedalong the negative z axis, as shown below.

You want to balance the magnetic force with an electric field so that the particle will continue along a straight line. The electric field should be in the

positive x direction
positive z direction
negative y direction
negative x direction
negative z direction
positive y direction


Q3: A circular 20 turn coil with a radius of 10 cm lies in the x-y plane and carries a current of 3 A. There is a uniform magnetic field of 0.5 T in the x-z plane directed at an angle of 36.9° from the x axis, as shown below.

The coil rotates so that its magnetic moment, μ, is aligned with the magnetic field. The potential energy of the system when the coil's magnetic moment is aligned with the field is

0.564 J
-0.942 J
-0.471 J
0.942 J
-0.564 J


Q4: A circular 10 turn coil with a radius of 5.0 cm lies in the x-y plane and carries a current of 5 A. There is a uniform magnetic field of 0.13 T in the x-z plane directed at an angle of 67.4° from the x axis, as shown below.

The coil rotates so that its magnetic moment, μ, is aligned with the magnetic field. The potential energy of the system when the coil's magnetic moment is aligned with the field is

0.086 J
0.051 J
0.028 J
-0.028 J
-0.051 J


Q5: Two loops carry equal currents I in the same direction. The loops are held in the positions shown in the figure and are then released. Which one of the following statements correctly describes the subsequent behavior of the loops?



Both loops move to the left.
The loops remain in the positions shown.
The top loop moves to the right; the bottom loop moves to the right.
The loops repel each other.
The loops attract each other.


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