MEASUREMENT OF UNKNOWN RESISTANCE BY DC CROMPTON'S POTENTIOMETER

i.                    Make the connection as per above figure in which R is an unknown resistance and S is known resistance.

ii.                  The current through a circuit is controlled with the help of a rheostat.

iii.                A two pole double throw switch is use. The switch, when put in position 1, 1’ connects the unknown resistance to the potentiometer. Therefore voltage across R is determined by D.C. Crompton’s potentiometer. V_r be the voltage across R.

iv.                When switch is thrown to position 2-2’, potentiometer measures voltage across known S. let V_s be the voltage across S.

v.                  Therefore resistance is measured by using below formula.

vi.                R = (V_R.S)/V_s