Chapter 7.2, Problem 3cT

A solenoid is an arrangement of many current loops placed together as shown below. The current through each loop is the same and is in the direction shown.

Obtain or draw an enlargement of the figure.

1. At each of the labeled points, draw a vector to indicate the direction and magnitude of the magnetic field. Use the principle of superposition in determine your answer.

2. Sketch magnetic field lines on the enlargement.

Describe the magnetic field near the center of the solenoid.

3. How does the field of the solenoid a points A-E compare with that of a bar magnet (both inside and outside?

Which end of the solenoid corresponds to a north pole? Which end corresponds to a south pole?

4. How would the magnetic field at any point within the solenoid be affected by the following changes? Explain your reasoning in each case.
• The current through each coil of the solenoid is increased by a factor of two.
• The number of coils in each unit length of the solenoid is increased by a factor of two, with the current through each coil remaining the same.