138 – Bell

Wagner’s hammer 

Introduction to:

electric bell, electromechanical bell 

Material:

Finished product, consisting of

• electromagnet
• bell
• clapper with metal spring
• interruptor

external batteries (4x 1.5V) required

How it works:

• When the circuit is closed, the metal spring is attracted by the electromagnet and the clapper strikes the bell.
• At the same time, the metal spring pulls on the interruptor, and thus the circuit is opened again. Consequently, the metal spring is no longer being attracted by the bell and relaxes again.
• Now the breaker closes the circuit again, and so on.

Didactic potential:

• Pupils make a bell using a kit: time-consuming, but with great learning value and good for dexterity.
• Pupils use a finished product: only those who have understood how it works can connect the cables correctly (series connection of electromagnet and breaker)