BITSAT 2018 Slot 2 Solved Paper

From the given circuit, we can say that I is independent of resistance R5, so no current flows through R5. This required that the junction of R1 and R2 is at the same potential as the junction of R3 and R4(∴ Wheatstone bridge condition)
So,

R1

R2

=

R3

R4

or R1R4=R3R2