VITEEE 2012 Paper

Given circuit is a balanced Wheatstone bridge.

Equivalent resistance of upper arms
= 2 + 2 = 4Ω
Equivalent resistance of lower arms
= 2 + 2 = 4Ω
∴ RAB =

4×4

4+4

= 2Ω   ( ∵ {R1 × R2}/{R1 + R2})