Question

In galvanometer, the deflection becomes the half when its is shunted by a $20\Omega$ resistor. The galvanometer resistance is ?

• A. $5\Omega$
• B. $10\Omega$
• C. $40\Omega$
• D. $20\Omega$

Answer 1

The correct option is D $20\Omega$

Voltage across galvanometer and $20\Omega$
resistor is same. Thus,

$\frac{i}{2}{R}_g=\frac{i}{2}\left(20\right)\Rightarrow R_g=20\Omega$

Hence, option (d) is the correct answer.

Why this question ? Key concept: In parallel combination voltage across the elements is same.