To measure the internal resistance of a battery, potentiometer is used. For R = 10 , the balance point is observed at  = 500 cm and for R = l  the

To measure the internal resistance of a battery, potentiometer is used. For R = 10 Ω, the balance point is observed at Ω = 500 cm and for R = l Ω the balance point is observed at Ω = 400 cm. The internal resistance of the battery is approximately : 

 (1) 0.2 Ω 

 (2) 0.4 Ω 

 (3) 0.1 Ω

 (4) 0.3 Ω                (JEE-2024)