Question

The resistance of a galvanometer is 199 . The sensitiveness is $2 \times 10^{-4}$ A per division. The scale contains 100 divisions. In order to convert it into an ammeter to
read up to $4 \mathrm{A},$ the shunt resistance is
(A) 0.5
(B) 1
(C) 2
(D) 3.5

Answer 1

We know that a galvanometer is an electromechanical instrument used for detecting and indicating an electric current. A galvanometer works as an actuator, by producing a rotary deflection (of a pointer), in response to electric current flowing through a coil in a constant magnetic field. Galvanometer, instrument for measuring a small electrical current or a function of the current by deflection of a moving coil. The deflection is a mechanical rotation derived from forces resulting from the current. If the south pole of the magnet is brought towards the solenoid, the galvanometer shows deflection. Current flows in the coil of the solenoid in the clockwise direction and the galvanometer shows deflection towards the left.

Complete step by step answer
Let us begin the answer by saying that:
$\mathrm{i}_{\mathrm{g}}$ for one division $=2 \times 10^{-4} \mathrm{A}$
$\mathrm{S}=\dfrac{\mathrm{i}_{\mathrm{g}} \mathrm{G}}{\left(\mathrm{i}-\mathrm{i}_{\mathrm{g}}\right)}$
Hence, we can say that:
So $\mathrm{i}_{\mathrm{g}}$ for 100 divisions $=2 \times 10^{-4} \times 100 \mathrm{A}$
$=2 \times 10^{-2} \mathrm{A}$
Therefore, we can say that:
$\mathrm{S}=\dfrac{\mathrm{i}_{\mathrm{g}} \mathrm{G}}{\left(\mathrm{i}-\mathrm{i}_{\mathrm{g}}\right)}$
After the putting the value we get that:
$=\dfrac{2 \times 10^{-2} \times 199}{4-2 \times 10^{-2}}$
$=1$ ohm

Hence the correct answer is option B.

Note Thus, it can be said that the major significant difference between ammeter and galvanometer is that ammeter shows only the magnitude of the current. Whereas, the galvanometer shows both the direction and magnitude of the current. Some of the different types of galvanometer include Tangent galvanometer, Astatic galvanometer, Mirror galvanometer and Ballistic galvanometer. To sum up, the sensitivity of the Moving Coil Galvanometer increases by the number of turns and the area of the coil, Increasing the magnetic induction and. Decreasing the couple per unit twist of the suspension fibre.