JEE Mains 26-July-2022 Shift 2 Solved Paper

A potentiometer wire of length 300‌cm is connected in series with a resistance 780Ω and a standard cell of emf 4V. A constant current flows through potentiometer wire. The length of the null point for cell of emf 20‌mV is found to be 60‌cm. The resistance of the potentiometer wire is ________ Ω