Physics - Current Electricity Question with Solution | TestHub

A Wheatstone's bridge is balanced with a resistance of $625\Omega$ in the third arm, where $P$, $Q$, and $S$ are in the 1ˢᵗ, 2ⁿᵈ, and 4ᵗʰ arm respectively. If $P$ and $Q$ are interchanged, the resistance in the third arm has to be increased by $51\Omega$ to secure balance. The unknown resistance in the fourth arm is