(N/A) The primary advantage of the null-point method in a Wheatstone bridge is that the position of the null point is independent of the internal resistance of the galvanometer. Consequently,there is no need to account for the galvanometer's resistance or the current flowing through it when determining the unknown resistance.
This method is also highly convenient and reduces errors for the observer.
If an alternative method,such as using Kirchhoff's laws,is employed to determine the unknown resistance,one would need to perform precise measurements of the current in all branches of the circuit. Additionally,the internal resistance of the galvanometer and the resistances of all individual components must be accurately known.
The balance condition for a Wheatstone bridge is given by $\frac{P}{Q} = \frac{R}{S}$,where $P$ and $Q$ represent the ratio of lengths,$R$ is the unknown resistor,and $S$ is the known resistor.