Physics Demonstrations at Cal Poly Pomona
Demo Index:
Pira Index:
Title:
Description:
Demonstrates current arc between two conductors.
Equipment:
1. Jacob’s ladder apparatus
2. Plexiglas tube
3. Variac
If it doesn’t work adjust the bottom gap between the 2 uprights to approx. 1 cm 140 v on variac may work a little better than the 120 v.
Procedure:
1. Place the plexiglas tube over upright posts to prevent accidentally coming in contact with them.
2. Plug the Jacob’s ladder into an AC source and watch the climbing spark.
How it works: A transformer steps the 115 V AC up to 10,000 V. The current arcs across the shortest distance between two upright conductors. Once started, the arc rises, owing to the heated air, and jumps over a distance of several inches.
