Topics of Interest CBSE Physics
Raj Kumar Parashari 29 Dec, 2019 Views: 330
Questions based on half deflection and conversion of galvanometer into voltmeter.
1. Why the scale of galvanometer has zero in the middle?
Ans. A needle at zero in the middle can deflect on both sides.
2. Why the divisions of a galvanometer scale are equally spaced?
Ans. Deflection in pointer is proportional to the current passed. The number of divisions in deflection will be proportional to the current passed. .
3. Define figure of merit of a galvanometer.
Ans. The quantity of current required to produce a deflection of one division in the galvanometer, is called figure of merit of the galvanometer. It is represented by the symbol. Its unit is ampere per division.
4. (a) Define current sensitivity of a galvanometer.
(b) How current sensitivity and voltage sensitivity can be increase.
Ans. (a) The deflection produced in the galvanometer when a unit current is passed through it, is called current sensitivity of the galvanometer.
(b) Refer to NCERT part -1 Page no. 165.
5. How are ‘figure of merit’ and ‘current sensitivity, related to each other?
Ans. They are reciprocal,
6. Why is the galvanometer called a moving coil galvanometer?
Ans. Because in this galvanometer, the coil moves (deflects), while the magnet remains fixed.
7. Why is this method called half deflection method?
Ans. It is so because the deflection is made half by using a shunt resistance S.
8. Under what conditions, G = S?
Ans. G = S, only when series resistance R is very high.
9. Which has lesser resistance – 1 ampere range ammeter or a 10 ampere range ammeter?
Ans. Higher the range, lower the resistance. A 10 A ammeter has lesser resistance.
10. Which has more resistance- 1 volt range voltmeter or a 10 volt range voltmeter?
Ans. Higher the range, higher the resistance. A 10 V voltmeter has higher resistance.
11. Write principle of working of galvanometer and how it can be converted into ammeter and voltmeter?
Ans. Refer to NCERT part -1 Page no. 165.
12. Can moving coil galvanometer be used to detect an a.c. in a circuit? Give reason.
Ans. It cannot be used to detect a.c. in a circuit since it measures the average value of current which is zero over a cycle.
13. Which has more resistance (a) Ammeter or voltmeter (b) milliammeter or ammeter (c) milli voltmeter or voltmeter.
Ans. (a) voltmeter, (b) milliammeter, (c) voltmeter.
14. What do you mean by the resistance of a galvanometer?
Ans. The resistance offered by the coil of a galvanometer to the flow of current through it is known as resistance (G) of the galvanometer.