Calibration of ammeter and voltmeter by potentiometer
1. What should be the size of slide wire of potentiometer to make achieve high accuracy
2. The length of wire in the potentiometer is 100 cm with a resistance of 30 ohms. It is connected in series with a resistance of 20 ohms and an accumulator of emf 8V having negligible internal resistance. 1.2 V source balances it against the length ‘L’ of the potentiometer wire. Calculate the length ‘L’ of the wire.
3.The balancing length of a potentiometer is at 120 cm. On shunting the cell with a resistance of 4 ohms, the balancing point shifts to a length of 60 cm. Then, find the internal resistance of the cell.
4. A potentiometer using cell C of emf 5V and internal resistance 0.2 ohms is connected to a wire AB in the figure below. A standard cell C0 of a constant emf of 1.10 V gives a balance point at 55 cm of the wire. When C0 is replaced by a cell of emf E, the balance point is obtained at 85 cm. What is the value of E?
5. A potentiometer has uniform potential gradient. The specific resistance of the material of the potentiometer wire is 10-9Ωm and the current passing through it is 0.5A and the cross-sectional area of the wire is 10-8m2. Calculate the potential gradient along the potentiometer wire.