Physics Demo Number: 164

Approximate

Run Time: 5 min

Arm-Powered Simple Generator

Demo Description

An old coil is equipped with flexible leads to attach it to a small DC bulb.

One holds the coil in one hand and vigorously thrusts it into and out of the field area of a strong permanent magnet.

If one has spent the proper amount of time to perfect his experimental technique, the bulb will be lit up by this simple generator.

Scientific Principles

• Changing magnetic field inside of a coil gives rise to induced emfs in the coil.

• If the coil is attached to a load, and if the rate of change of the field is large enough, then one may produce current flow in the load.

Equipment

• An old black-tape-wrapped coil

• A strong horseshoe magnet

• A small bulb in a socket

Equipment Location

• Kit (164) on [B-1-3] houses the coil and bulb components.

• The magnet is on [B-4-1].

Instructions

The components are pictured in the photo.

One holds the coil in one hand and vigorously thrusts it into and out of the field area of the strong magnet.

Lots of practice and technique are usually necessary to actually get the demo to work smoothly.

Writeup created by David A. Burba

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