Question

The resistance of a galvanometer is 2.5 ohm and it requires 50 mA for full scale deflection. The value of shunt required to convert it into an ammeter of 5A range is nearly

• A. $2.5\times {10}^{-2}ohm$
• B. $1.25\times {10}^{-3}ohm$
• C. 0.05 ohm
• D. 2.5 ohm

Answer 1

The correct option is A $2.5\times {10}^{-2}ohm$

Let resistance of shunt be x

= $Req=\frac{G_x}{G+x}=\frac{2.5x}{2.5+x}$ (we have used the standard euation in case of galvanometer according to question)

$\frac{i_1}{i_2}=\frac{R_2}{R_1}=\frac{50\times {10}^{-3}}{5}=\frac{x}{2.5+x}$

= 100x = 2.5+x

99x=2.5

$x=2.5\times {10}^{-2}\Omega$