School of Physics Lecture Demonstration Manual

Ea-6 The Current Balance (Including the Kelvin Balance)

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

Aim

To demonstrate the current balance; a device for the absolute measurement of current.

Apparatus

Diagrams

Click on pictures to enlarge.

Current Balance Diagram

Description

The apparatus consists of a balance with a fixed coil B and a coil C suspended from one arm of the balance. The current to be measured passes through the coils such that the force is attractive. Balance is restored by the addition of weights to the pan on the other arm.

A Kelvin deci-ampere balance for measurements in the range 1/10 - 1 Ampere is also available.

Safety notes

Electrical safety 

Miantenance 

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