10 Question-answer on potentiometer
1. The length of a potentiometer wire is 5 meters. An electron in this wire experiences a force of 4.8 × 10-19 newton, e.m.f. of the main cell used in potentiometer is:
(a) 3 volt
(b) 15 volt
(c) 1.5 volt
(d) 5 volt
Ans: (b)
2. A 10 m long wire of resistance 20Ω is connected in series with a battery of e.m.f. 6 V and resistance of 10Ω. The potential gradient along the wire in volt per metre is:
(a) 0.4
(b) 1 V
(c) 0.2
(d) 1.2
Ans: ( a)
3. In a potentiometer experiment the balancing length with a cell in open circuit is 250 cm. on shunting the cell with a resistance of 2 Ω, the balancing length becomes 200 cm. the internal resistance of the cell is:
(a) 0.1Ω
(b) 0.5 Ω
(c) 1 Ω
(d) 2Ω
Ans: (b)
4. In a potentiometer experiment for measuring the e.m.f. of a cell, the null point is at 480 cm when we have a 400Ω resistor in sries with the cell and galvanometer. If the series resistances is reduced to half, the null point will be at:
(a) 120 cm
(b) 240 cm
(c) 480 cm
(d) 600 cm
Ans: ( c)
5. In a potentiometer of 10 wires, the balance point is obtained on the 7th wire. To shift the balance point to 9th wire, we should
(a) Decrease resistance in the main circuit
(b) increase resistance in the main circuit
(c) Decrease resistance in series with the cell whose e.m.f. is to be measured
(d) increase resistance in series with the cell whose e.m.f. is to be determined
Ans: (b)
6. in potentiometer a balance point is obtained, when
(a) the e.m.f. of the battery becomes equal to the e.m.f. of the experimental cell
(b) the p.d. of the wire between the +ve end to jockey becomes equal to the e.m.f. of the experimental cell
(c) the p.d. of the wire between the +ve point and jockey becomes equal to the e.m.f. of the battery
(d) the p.d. across the potentiometer wire becomes equal to the e.m.f. of the battery
Ans: (b)
7. in the experiment of potentiometer, at balance, there is no current in the
(a) main circuit
(b) galvanometer circuit
(c) potentiometer circuit
(d) both main and galvanometer circuit
Ans: ( b)
8. if the applied emf in the main circuit of a potentiometer is increased three times then the value of potential gradient will become
(a) one third
(b) three times
(c) six times
(d) two times
Ans: ( b)
9. if the radius of a potentiometer wire is increased four times, keeping its length constant then the value of its potential gradient will become
(a) half
(b) two times
(c) four times
(d) constant
Ans: ( d)
10. for the higher sensitivity which of the following is essential for the potentiometer
(a) larger length of wire
(b) higher resistivity of the wire
(c) higher e.m.f. of auxiliary battery
(d) none of above
Ans: ( a)