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A fully charged mobile phone with a $12 \mathrm{~V}$ battery is good for a $10$ minute talk-time. Assume that, during the talk-time, the battery delivers a constant current of $2 \mathrm{~A}$ and its voltage drops linearly from $12 \mathrm{~V}$ to $10 \mathrm{~V}$ as shown in the figure. How much energy does the battery deliver during this talk-time ?

1. $220 \mathrm{~J}$
2. $12 \mathrm{~kJ}$
3. $13.2 \mathrm{~kJ}$
4. $14.4 \mathrm{~kJ}$