Physics Demo Number: 134

Approximate

Run Time: 5 min

Hand Operated Generators

Demo Description

By cranking a small AC generator under 'no load' and 'load' conditions one can show that mechanical energy or work must be fed into the generator to get useful current out.

Scientific Principles

• One can convert mechanical energy to electrical energy by rotating coils inside of a magnetic field.

Equipment

• Two hand-cranked AC generators

Equipment Location

• Kit (134) on [B-3-5]

Instructions

The photo shows two hand operated AC Generators with "AC light bulb" loads.

The smaller one's crank handle can easily be spun rapidly with the load switch open.

When the handle is released while it is being spun rapidly, one observes a several seconds spin down time of the handle.

This contrasts with the difficulty of approaching even a fraction of the cranking speed with the load switch closed, and the almost instantaneous stopping of the handle's spin upon releasing it under closed switch conditions.

[B-3-5] is the normal location of the hand-cranked generators.

Writeup created by David A. Burba

Copyright © 2011, Vanderbilt University.   All Rights Reserved.