Two galvanometers have identical characteristics. One of them is converted into a milliammeter and the other into a microammeter. The shunt resistance of microammeter as compared to milliammeter will be:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → more
A galvanometer is converted into an ammeter of range I by connecting a shunt S in parallel. The shunt carries the current \( I - I_g \) and the galvanometer carries \( I_g \), at the same potential difference.
\( I_gG = (I - I_g)S \)
\( \displaystyle S = \frac{I_gG}{I - I_g} \)
The two galvanometers are identical, so \( I_g \) and G are the same. A microammeter has a much smaller range I than a milliammeter, so \( I - I_g \) is smaller and the shunt resistance is larger.