Physics Demonstrations at Cal Poly Pomona
Demo Index:
Pira Index:
Title:
ELECTRO-MAGNETIC RAIL DEMO
Description:
Demonstrates the interaction between an electric current and a magnetic field or a simple monopole motor.
Equipment:
1. Train track
2. Brass rod (internal magnets)
3. 1D-cell (or C-cell)
4. Metal battery holder
5. 2 B-A leads
CLEAN THE RAIL & CONNECTING POINTS ON THE ROD W/ A PENCIL ERASER
Procedure:
1. Set up as shown. Be sure all conducting surfaces are cleaned w/ pencil eraser & soft cloth.
2. Touch the leads to the ends of the cells and the rod rolls down the track. Touch the leads to the opposite ends of the cells and the rod reverses its direction.
•The magnet rod is made by putting two small cylindrical magnets into a copper tube so that like poles point out at each end of copper tube. When they are aligned as in diagram below and current flows as shown, using right-hand rule, force applied on bottom of tube gives it a forward torque, top a backward torque, and rod would roll to left.
