JEE Main 2025 Apr 2 Shift 1, Physics Q8: Energy, Power And Heating Effect

The energy stored in a battery is the product of its voltage and total charge capacity:

$$E=V\times Q$$

Convert capacity from mAh to coulombs: $1\text{Ah}=3600\text{C}$.

$$Q=5800\text{mAh}=5.8\text{A}\times 3600\text{s}=20880\text{C}$$

$$E=4.2\times 20880=87696\text{J}\approx 87.7\text{kJ}$$

$\therefore$ Option (3) is correct.