An ammeter of resistance \( 0.54\,\Omega \) reads current up to 1 A. The value of the shunt required to increase the range to 10 A is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → \( 0.06\,\Omega \)
A shunt is a small resistance joined in parallel with the ammeter. At full scale the ammeter still carries its own range \( I_g = 1\,\mathrm{A} \), and the shunt carries the rest, \( I - I_g \). Both have the same potential difference across them.
\( \displaystyle I_g\,G = (I - I_g)\,S \)
\( \displaystyle S = \frac{I_g\,G}{I - I_g} = \frac{1\,\mathrm{A} \times 0.54\,\Omega}{(10 - 1)\,\mathrm{A}} = 0.06\,\Omega \)