The resistance of a galvanometer is 30 Ω. It gives full scale deflection for 2 mA. It is to be converted into an ammeter to measure current 0.3 A. The value of the shunt required is approximately

0.2 Ω

The correct answer is Option (1) → 0.2 Ω

Given:

Resistance of galvanometer, $R_g = 30\,\Omega$

Full-scale deflection current, $I_g = 2\,mA = 2 \times 10^{-3}\,A$

Total current to be measured, $I = 0.3\,A$

Let shunt resistance be $R_s$.

Current through shunt: $I_s = I - I_g = 0.3 - 0.002 = 0.298\,A$

Since the voltage across galvanometer and shunt are equal:

$I_g R_g = I_s R_s$

Hence,

$R_s = \frac{I_g R_g}{I_s}$

Substitute values:

$R_s = \frac{2 \times 10^{-3} \times 30}{0.298}$

$R_s = \frac{0.06}{0.298} = 0.201\,\Omega$

Final Answer: $R_s \approx 0.2\,\Omega$