The Annapurna scheme, initiated in India, is a part of the Food Security Programmes. This scheme specifically targets the food security needs of the subset of the elderly population living below the poverty line. Under this scheme, eligible beneficiaries receive free food grains, ensuring basic nutritional security. This program aligns with the broader aim of ensuring food availability to vulnerable sections of society.
A battery of emf \( E \) and internal resistance \( r \) is connected to a rheostat. When a current of 2A is drawn from the battery, the potential difference across the rheostat is 5V. The potential difference becomes 4V when a current of 4A is drawn from the battery. Calculate the value of \( E \) and \( r \).