A battery of emf E and internal resistance r gives a current of 0.5 A with an external resistor of 1202 and a current of 0.25 A with an external resistor of 259. A battery of emf E and internal resistance r gives a current of 0.5 A with an external resistor of 1202 and a current of 0.25 A with an external resistor of 259. Calculate (a) internal resistance
Calculate internal resistance.