Current Electricity

In order to measure the internal resistance r₁ of a cell of emf E, a meter bridge of wire resistance R₀ = 50\(\Omega\), a resistance R₀/2, another cell of emf E/2 (internal resistance r) and a galvanometer G are used in a circuit, as shown in the figure. If the null point is found at l = 72 cm, then the value of r₁ = __________ \(\Omega\).