Back to table of contents Conceptual Questions

Conceptual Questions

12.1 The Biot-Savart Law

1.

For calculating magnetic fields, what are the advantages and disadvantages of the Biot-Savart law?

2.

Describe the magnetic field due to the current in two wires connected to the two terminals of a source of emf and twisted tightly around each other.

3.

How can you decide if a wire is infinite?

4.

Identical currents are carried in two circular loops; however, one loop has twice the diameter as the other loop. Compare the magnetic fields created by the loops at the center of each loop.

12.2 Magnetic Field Due to a Thin Straight Wire

5.

How would you orient two long, straight, current-carrying wires so that there is no net magnetic force between them? (Hint: What orientation would lead to one wire not experiencing a magnetic field from the other?)

12.3 Magnetic Force between Two Parallel Currents

6.

Compare and contrast the electric field of an infinite line of charge and the magnetic field of an infinite line of current.

7.

Is B constant in magnitude for points that lie on a magnetic field line?

12.4 Magnetic Field of a Current Loop

8.

Is the magnetic field of a current loop uniform?

9.

What happens to the length of a suspended spring when a current passes through it?

10.

Two concentric circular wires with different diameters carry currents in the same direction. Describe the force on the inner wire.

12.5 Ampère’s Law

11.

Is Ampère’s law valid for all closed paths? Why isn’t it normally useful for calculating a magnetic field?

12.6 Solenoids and Toroids

12.

Is the magnetic field inside a toroid completely uniform? Almost uniform?

13.

Explain why B=0 inside a long, hollow copper pipe that is carrying an electric current parallel to the axis. Is B=0 outside the pipe?

12.7 Magnetism in Matter

14.

A diamagnetic material is brought close to a permanent magnet. What happens to the material?

15.

If you cut a bar magnet into two pieces, will you end up with one magnet with an isolated north pole and another magnet with an isolated south pole? Explain your answer.

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