JEE Main 30 June 2022 Shift 1 Solved Paper

The circuit diagram of potentiometer used to measure the internal resistance of a cell (E) is shown in figure. The key ' K ' is kept closed so as to send constant current through potentiometer wire. When key ' K1 ' is kept open the null point is found to be at 120‌cm on the potentiometer wire. When the key ' K1 ' is closed the null point is shifted at 80‌cm at the potentiometer wire. The internal resistance of the given cell is_____ Ω