School of Physics Lecture Demonstration Manual

Ea-5 The Electromagnetic Pump

Published: Tuesday 14 March 2006 - Updated: Tuesday 29 March 2011


To demonstrate the magnetic force on an electric current (in a fluid) using a simple electromagnetic pump.



Click on pictures to enlarge.

EM Pump Diagram


Electromagnetic Pump


 a) Principle of Physics illustrated. 

An electric current experiences a force at right angles to both the current direction and the magnetic field.

F = force per unit volume

= J × B J = current density

 b) Procedure 

The mercury kept in the chemical cupboard is funnelled into the electromagnetic pump to the top of the smaller channel.

Approximately 3-5V D.C. is applied to the binding posts from the D.C. supply fitted to the lecture bench, (The switch in the basement for the D.C. supply must be turned to the correct position for operation).

It is advisable not to allow operation of the pump for longer than 30 seconds as it is drawing quite a large current.

Safety notes

Electrical Safety 

Chemical Safety 


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