Question

The P.D between A and B will be zero when the resistance R is

• A. 4.5 ohm
• B. 12 ohm
• C. 9 ohm
• D. 6 ohm

Answer 1

The correct option is A 4.5 ohm

From the circuit, using the balanced Wheatstone bridge condition,
$\frac{15}{4}=\frac{R+3}{2}15=2R+6R=\frac{9}{2}=4.5\Omega$