Question

Define the current sensitivity of a galvanometer. Write its S.I unit.

Answer 1

In this question, we want to know about the current sensitivity of a galvanometer. A galvanometer is a device used to detect the current and the current sensitivity shows the deflection when the current source is applied across the galvanometer. The S.I unit of the current sensitivity is radians per ampere.

Complete answer:
Firstly, learning about what a galvanometer is. A galvanometer is a device that is used to detect the amount of current. And now, Current sensitivity is defined as when the current flows through the galvanometer coil and the coil shows deflection. Mathematically, it is represented as ${I_S} = \dfrac{\theta }{I}$ where $\theta$ is the deflection per unit current and this expression is also represented as ${I_S} = \dfrac{{nBA}}{\tau }$ where n is the number of turns in the coil, B is the magnetic field around the coil, A is the cross-sectional area of the coil and $\tau$ is the restoring torque.The S.I unit of current sensitivity is radians per ampere.

Note: In the similar way, voltage sensitivity is defined as the how much deflection is shown by the galvanometer when some potential difference is applied across it. As seen from the question, we come to know that the current sensitivity is independent of the resistance. Whereas, voltage sensitivity depends inversely on the resistance applied across the galvanometer.