Potentiometer (Potential Gradient)
A 10m long wire of 20 ῼ resistance is used as a potentiometer wire This wire is connected with a 5V battery along an external resistance of 480 ῼ If an unknown emf E is balanced at 600 cm calculate 1) potential gradient 2) the value of E 1) The total resistance =480+20 = 500 ῼ So the current in the circuit=5/500=1/100 A Potential drop across the wire= 20 × (1/100)=1/5 V . . . Potential Gradient =potential drop per unit length= (1/5) / 10= 1/50 v/m 2) The unknown emf E= Potential gradient × Balancing length E =(1/50) × 6= 6/50 V