Wire Length Calculation

Students can get some practical experience with calculation by determining the length of wire that is needed for each coil of the metal detector. An example of how to proceed with the calculation is shown below.

Choose a plastic container to wrap wire for the metal detector. Measure the top diameter and bottom diameter.

In this case the top is 11.5 cm and the bottom is 8.9 cm.

If we wrap the coil in the middle of the container. the diameter will be the average of these two:  (11.5+8.9) /2 = 10.2 cm

To find the circumference, use pi X D, or 3.14 X 10.2 = 32.028 cm/ wrap.  

For 20 turns, we need 20 X 32.08 cm = 640.56 cm

To find the number of feet, divide by 25.4 = 25 feet.

Add 6 inches for each for hook up for a  total length of 26 feet

Return to Recreate Bell's Metal Detector.