Presenter: Tony Wayne
Albemarle High School , twayne[at symbol]k12albemarle.org
PH.12 The student will investigate and understand how to use the field concept to describe the effects of electric, magnetic, and gravitational forces.
A force is needed to move any object.
1 - doorbell for Lowes or Home Depot. ($10)
1 – pliers
1 – wire cutters
1 – piece of wood to mount the doorbell on
5 – 5/8” long number 6 screws
9 – Volt battery
Make sure the battery is not left somewhere in a position where the terminals are shorted.
- The completed unit is set up a station where students are asked to explain how a door bell works.
- This could also be done as a classroom demonstration. A 9 Volt battery will ring the doorbell but it is designed for a 12 Volt battery. A 12 Volt battery rings the doorbell with more volume. A twelve Volt battery can be made from two six Volt lantern batteries wired in series.
How the physics is demonstrated
When the coils are energized by the battery they generate a magnetic field inside them according to Ampere's rule. The metal rods inside the coil are steel and are attacted. This pulls hte rods into and through the coil to hit a bell. When the current is turned off, the spring wrapped around the coil pulls the rod back into place and overshoots the equalibrium position and hits the other bell. before coming to a rest in the equalibrium position.