Question

A galvanometer of resistance $25\Omega$ gives full scale deflection at 10mA current. It is used as Ammeter with two terminals A and B as shown in figure. One of the terminals (i.e either A or B) is used at a time. Find ratio of range of Ammeter when used between terminal A to terminal B. i.e Find $\frac{I_A}{I_B}.$

• A. 5
• B. 2
• C. 6
• D. 3

Answer 1

The correct option is A 5


$V_{PA}=10\times {10}^{-3}\times 27=(I_A-{10}^{-2})\times 0.5$
$I_A=0.55A$ ...(1)

$V_{PB}={10}^{-2}\times 25=(I_B-{10}^{-2}\times 2.5)$
$I_B=0.11$
$\frac{I_A}{I_B}=5$