# Voltage and Current Sensitivity of a Galvanometer

Current Sensitivity:

The deflection of a galvanometer per unit current is called current sensitivity of galvanometer.

$$\text{i.e., } S_I = \frac{ \theta }{I}……(i)$$

In a moving coil galvanometer,

$$k \theta =BINA$$

$$or, \frac{ \theta }{I}= \frac{BNA}{k}$$

From equation (i) and (ii),

$$S_I = \frac{BNA}{k}$$

So, current sensitivity of a galvanometer can be increased by increasing the value of B, N and A. It can be decreased by decreasing the value of k.

Voltage Sensitivity:

The deflection of galvanometer per unit voltage is called voltage sensitivity of a galvanometer.

$$\text{i.e., } S_v = \frac{ \theta }{V}……(i)$$

In a moving coil galvanometer,

$$k \theta =BINA$$

$$or, K \theta = B \frac{V}{R}NA$$

$$or, \frac{ \theta }{V} = \frac{BNA}{Rk}$$

So, voltage sensitivity of a galvanometer can be increased by increasing the value of B, N and A. It can be decreased by decreasing the value of R and k.

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#### 4 Responses to “Voltage and Current Sensitivity of a Galvanometer”

1. David

Please endeavor to define the terms in the equations

2. Harsha raibagi

What is the range of figure of merit of ballistic galvanometer?

3. Sai Charan Reddy

Try to derive the terms in it

4. chalani rasangi