Suggested languages for you:

Q. 79

Expert-verified
Found in: Page 835

### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

Book edition 4th
Author(s) Randall D. Knight
Pages 1240 pages
ISBN 9780133942651

# You have a 1.0-m-long copper wire. You want to make an N-turn current loop that generates a 1.0 mT magnetic field at the center when the current is 1.0 A. You must use the entire wire. What will be the diameter of your coil?

.

See the step by step solution

## Step 1. Given information

The total length of the copper wire is , the current through the wire is and the magnetic field at the center of the coil is .

## Step 2. Calculation

The formula to calculate the total length of the wire can be written as

Here, is the total length of the wire, i the number of turns when the wire is bent into a circular loop and is the diameter of the loop.

Simplify equation (1) to obtain the number of turns in the loop.

The formula to calculate the magnetic field at the center of a circular loop is given by

Here, is the magnetic field, is the permeability of free space and is the current through the loop.

Substitute the expression for the number of turns from equation (2) into equation (3) and simplify to obtain the diameter of the loop.

Substitute for , for , for and for into equation (4) to calculate the required diameter.