Question

$\text{ The Wheatstone bridge is an arrangement of four resistances, say } R_1, R_2, R_3, \text{ and } R_4. \text{ The null point condition is given by:}$

• A. $\quad \frac{R_1}{R_2} = \frac{R_3}{R_4} \\\\$
• B. $\quad R_1 + R_2 = R_3 + R_4 \\\\$
• C. $\quad R_1 - R_2 = R_2 - R_4 \\\\$
• D. $\quad R_1 \times R_2 = R_3 \times R_4$

Answer 1

Answer: (A)

$\quad \frac{R_1}{R_2} = \frac{R_3}{R_4} \\\\$

Answer 2

The Wheatstone bridge is balanced when the ratio of the two resistances in one branch equals the ratio of the two resistances in the other branch:
$\quad \frac{R_1}{R_2} = \frac{R_3}{R_4} \\\\$This is the condition for zero current through the galvanometer.