Question

1. Computer cables create little to no magnetic field because they are comprised of closely spaced wires carrying oppositely directed currents. (True -False)

2. The magnetic field of a short segment of current-carrying conductor is due primarily to the random motions of the charges moving through the segment. (True -False)

3. A current element that is directed out of the page produces magnetic field lines that form clockwise circles. (True- False)

4. Iron, nickel, and cobalt have relative permeabilities that are much larger than one, and so they are categorized as ________________ [one word] materials.

5. Consider a long and straight cylindrical conductor carrying a current. We are interested in the magnetic field at a radius r from the center of this conductor. Which of the following statements is true for the magnetic field?

1. Outside the conductor, the magnitude of the magnetic field scales in proportion to r.
2. Inside the conductor, the magnitude of the magnetic field scales in proportion to r.
3. Inside the conductor, the magnitude of the magnetic field scales in proportion to r².
4. Outside the conductor, the magnitude of the magnetic field scales in proportion to r².

6. If the number of turns in a coil doubles, the magnetic field does what?

1. Quadruples
2. Doubles
3. stays the same
4. halves
5. quarters

7. Two parallel wires carrying current in (Same direction/ Opposite Direction)

attract, while two parallel wires carrying current in (Same direction/ Opposite Direction) repel.

8. Gauss's law is of greatest use in finding the electric field due to a symmetric charge distribution. Analogously, Ampère's law is of greatest use in finding the……………… [one word] field due to a symmetric ………. [one word] distribution.

9. Mutual forces of attraction exist between current elements within a single conductor. When the conductor is a liquid or a plasma, these forces result in a constriction of the conductor. This self-constriction phenomenon is called the ___________________ [one word] effect

10. The magnetic field along the axis of a circular coil decays with distance as 1/r³ (when the field is far away from the coil). (True/ False).