# Finding north with copper wire

1. Aug 23, 2013

### MmeCurie

How do you figure out which way is north when you're lost and the only things you've got with you is a copper wire and a voltmeter?

2. Aug 24, 2013

### sophiecentaur

1. What happens when you wave a copper wire about in a magnetic field?
2. When is this effect most and when is it least?

Answer those two questions and you're on the way to a solution.

3. Aug 28, 2013

### Andrew Mason

Make a loop of the largest area that you can make with the copper wire and voltmeter leads (connected to the voltmeter) using your arms while orienting the loop vertically. Then, standing up, turn around as fast as you can but at constant rotational speed while watching the voltmeter.

Since the earth's magnetic flux through the loop is changing as you turn, there will be an induced emf around the loop. The magnitude of that induced emf is proportional to the rate of change of that flux. At what point in your turn (letting 0 degrees be due magnetic north) will the time rate of change of magnetic flux be maximum (ie. where you will observe maximum deflection of the voltmeter)? Figure out north from that.

AM