Force on Conductor & Galvanometer — Practice Questions

Free NEET Physics multiple-choice questions on Force on Conductor & Galvanometer. Attempt each question and reveal the answer with a full explanation.

The resistance of an ideal ammeter is: Zero Infinite Small but non-zero Large An ideal ammeter should have: Zero resistance Infinite resistance Low resistance High resistance A galvanometer can be converted into an ammeter by connecting a low resistance in parallel. If the resistance of the galvanometer is G and the shunt resistance is S , the resistance of the ammeter is: GS G+S G+S G+S GS G-S If the current sensitivity of a galvanometer is S i and its resistance is G , its voltage sensitivity S v is given by: S i / G S i G G / S i 1 / (S i G) The unit of the 'Figure of Merit' of a galvanometer is: Ampere per division Division per Ampere Volt per division Ohm per division The soft iron core in a moving coil galvanometer is used to: Make the magnetic field radial and strong Reduce the resistance of the coil Increase the damping Reduce the weight of the instrument A galvanometer has a resistance of G and a current i g for full scale deflection. It is converted into an ammeter by a shunt S . The equivalent resistance of the ammeter is: GS/(G+S) G+S G-S GS/(G-S) Current sensitivity of a moving coil galvanometer is 5 div/mA and its voltage sensitivity (angular deflection per unit voltage applied) is 20 div/V. The resistance of the galvanometer is 250 Ω 25 Ω 40 Ω 500 Ω A galvanometer of resistance 100 gives full scale deflection for a current of 1 mA. It is converted into an ammeter of range 0 –10 A. The shunt required is: 0.001 0.10 1.0 0.01 A galvanometer having a resistance of 100 Ω gives full scale deflection for a current of 10 mA. What resistance should be connected in series to convert it into a voltmeter of range 100 V? 9900 Ω 10000 Ω 900 Ω 1000 Ω A galvanometer of resistance G is shunted by a resistance S . The fraction of total current passing through the galvanometer is: S / (G + S) G / (G + S) (G + S) / S (G + S) / G The 'Figure of Merit' of a galvanometer is k . If the current sensitivity is S i , then: k = 1/S i k = S i k = S i 2 k = S i When a current sensitivity of a galvanometer is increased by 20%, the voltage sensitivity: May or may not change Also increases by 20% Decreases by 20% Remains unchanged An ammeter of resistance 0.80 can measure current up to 1.0 A. To extend its range to 5.0 A, the required shunt resistance is: 0.20 0.25 0.10 0.50 A galvanometer of resistance G is converted into an ammeter using a shunt of resistance S . If the range of the ammeter is n times the range of the galvanometer, the value of S is: G/(n-1) G/n G(n-1) nG If the number of turns in a moving coil galvanometer is doubled, then: Current sensitivity is doubled, but voltage sensitivity remains same Both current and voltage sensitivity are doubled Current sensitivity remains same, but voltage sensitivity is doubled Both remain unchanged A galvanometer of resistance 100 is converted into an ammeter of range 10 times its initial range. The value of the shunt resistance required is: 11.11 10 0.1 100 The 'Figure of Merit' of a galvanometer is defined as: The current required to produce unit deflection The deflection produced by unit current The resistance of the galvanometer The voltage required for unit deflection If a galvanometer of resistance G is shunted by a resistance S , the fraction of the total current that flows through the shunt is: G G+S S G+S G-S G G S A galvanometer has a sensitivity of 5 divisions per milliampere and its resistance is 40 . If it is connected to a shunt of 10 , the new sensitivity of the combination is: 1 division per mA 4 divisions per mA 25 divisions per mA 0.8 divisions per mA To reduce the current in a circuit to 1/10 th of its value using a galvanometer of resistance G , the shunt resistance S required is: G/9 G/10 G/11 9G The soft iron core in a galvanometer serves two purposes. One is to increase the magnetic field strength, and the other is to: Make the magnetic field radial Reduce the weight of the instrument Increase the resistance of the coil Prevent eddy currents A galvanometer with a resistance of 12 shows a full-scale deflection for a current of 3 mA. To convert it into a voltmeter of range 0 to 18 V, the series resistance required is: 5988 6000 5976 6012 In an ammeter 0.2 % of main current passes through the galvanometer. If resistance of galvanometer is G, the resistance of ammeter will be :- 1 499 G 499 500 G 1 500 G 500 499 G A galvanometer of resistance 50 is connected to a battery of 3 V along with a resistance of 2950 in series. A full scale deflection of 30 divisions is obtained. In order to reduce this deflection to 20 divisions, the resistance in series should be: 4450 5050 6010 4500 A sensitive galvanometer is converted into an ammeter of range I using a shunt S . If the range is to be doubled to 2I , the new shunt resistance should be: Less than S/2 More than S/2 Exactly S/2 Exactly 2S Two infinitely long parallel conducting wires A and B carry currents I and 2I , respectively, in the same direction. The wire A has uniform mass per unit length and lies on an insulated floor. The wire B is kept fixed at a height h above the floor. The minimum magnitude of h so that the wire A does not rise from the floor is: [ g is the acceleration due to gravity and 0 is the permeability of free space.] 0 I 2 2 g 0 I 2 g 2 0 I 2 g 4 0 I 2 g In a moving coil galvanometer, the deflection is related to the current I by the relation: I = (k/NAB) I = (NAB/k) I = (k/NAB) I = (k/NAB) Which of the following is the reason for using a phosphor-bronze strip in a moving coil galvanometer? It has a small torsional constant It is a good conductor of electricity It has high tensile strength It is not affected by magnetic fields In a moving coil galvanometer, the current I is related to the deflection as I = k . The constant k is: Figure of merit Current sensitivity Voltage sensitivity Torsional constant The current sensitivity of a moving coil galvanometer depends on: The magnetic field strength The resistance of the coil The applied voltage The thickness of the wire A sensitive galvanometer can be used as a voltmeter by connecting a: High resistance in series Low resistance in series High resistance in parallel Low resistance in parallel The reason for using a radial magnetic field in a moving coil galvanometer is: To make the scale linear To increase the sensitivity To decrease the resistance To prevent eddy currents