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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One Response to “Voltage and Current Sensitivity of a Galvanometer”

  1. David

    Please endeavor to define the terms in the equations