Supplementary notes on E&C covered under further resources
In these days, digital multimeter helps in measuring the resistance in a simple way. But the advantage of Wheatstone bridge over this is to provide the measurement of very low values of resistance in the range of milli-ohms.
The Wheatstone bridge is the interconnection of four resistances forming a bridge. The bridge is used for finding the value of an unknown resistance connected with two known resistor, one variable resistor and a galvanometer.
To find the value of unknown resistance the deflection on galvanometer made to zero by adjusting the variable resistor.
- For example, if the voltage achieved is 0 when the potentiometer is at 40% (2Kohm), then replace the potentiometer with a resistor having 2Kohm.
This point is known as the balance point of Wheatstone bridge. In the balanced condition:
- No current flowing through galvanometer
- same current I1 will flow thorough R1 and R2.
- current I2 thorough R3 and Rx will remain same.
Rx = (R2 * R3) / R1