Discussion Forum



1)

A galvanometer has a current range of 15 mA and voltage range of 750mV. To convert this galvanometer into an ammeter of range 25 A, the required shunt is 


A) $0.8 \Omega$

B) $0.93 \Omega$

C) $0.03 \Omega$

D) $2.0 \Omega$

Answer:

Option C

Explanation:

Given : V=$750 \times 10^{-3}$V;

$I_{g}=15 \times 10^{-3} A$ and I=25 A

Using  , $a= \frac{y}{I_{g}}$

                 $= \frac{750 \times 10^{-3}}{15 \times 10^{-3}}=50 \Omega$

 $I_{g}=\frac{S}{S+a} \times I$

 $15 \times 10^{-3}=\left(\frac{S}{S+50}\right)\times25$

$\therefore$    $S=0.03 \Omega$