Why the balance-point to be in the middle third in experiments with a slide-wire bridge?

In experiments using a slide-wire bridge, the balance point is located in the middle third to ensure that the bridge remains stable and sensitive to changes in resistance. This position allows for equal distribution of weight and minimizes the effects of external forces, providing an accurate measurement of the unknown resistance. Additionally, positioning the balance point in the middle third enhances the precision of the null point detection, leading to more reliable experimental results.