Calibration of ammeter and voltmeter by potentiometer
1) What should be the size of slide wire of potentiometer to make achieve high accuracy
2) A potentiometer wire of length 100 cm has a resistance of 30 ohms. It is connected in series with a resistance of 20 ohms and accumulator of emf 8V having negligible internal resistance. A source of 1.2V is balanced against a length L of the potentiometer wire. What is the value of L?.
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.