Potentiometer circuit looks complicated but if you look carefully it contains two separate circuits. Solving the two circuits separately is the key to solving potentiometer problems.
Find out about the potentiometer circuit and make calculations to determine the p.d across 1 m resistance wire. If more than 1 m than find voltage across wire for L meters.
Go to the lower circuit to find out the p.d across the two point that are connected to the potentiometer via a galvanometer. Equate these two potential diference , the one across the wire (at balance length ) and the one across the circuit to be measured.These two p.d are the same as it is shown by the galvanometer (zero reading) when balance length is reached.
This matching of two circuit needs to be understood. Potentiometer is a voltmeter that mesures in length and needs to be calibrated . No current cross from potentiometer to the circuit to be measured. That is why it is such a good meter to measure p.d.
A normal voltmeter would require some current to be drawn from the circuit thereby causing inaccuracy in measuring the p.d.
Find out about the potentiometer circuit and make calculations to determine the p.d across 1 m resistance wire. If more than 1 m than find voltage across wire for L meters.
Go to the lower circuit to find out the p.d across the two point that are connected to the potentiometer via a galvanometer. Equate these two potential diference , the one across the wire (at balance length ) and the one across the circuit to be measured.These two p.d are the same as it is shown by the galvanometer (zero reading) when balance length is reached.
This matching of two circuit needs to be understood. Potentiometer is a voltmeter that mesures in length and needs to be calibrated . No current cross from potentiometer to the circuit to be measured. That is why it is such a good meter to measure p.d.
A normal voltmeter would require some current to be drawn from the circuit thereby causing inaccuracy in measuring the p.d.
