Current Electricity

JEE Main level, single correct, medium

227 of 380

Question 227 of 380

The battery of a mobile phone is rated as 4.2 V , 5800 mAh. How much energy is stored in it when fully charged ?

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Answer: (C) 87.7 kJ

Given V=4.2\mathrm{V}=4.2 volt
∴\therefore Energy supplied by battery
=vq=4.2×5800×3600×10−3 J=87.696 kJ=\mathrm{vq}=4.2 \times 5800 \times 3600 \times 10^{-3} \mathrm{~J}=87.696 \mathrm{~kJ}
∴\therefore Energy stored in the battery when fully charged
=87.696 kJ≈87.7 kJ=87.696 \mathrm{~kJ} \approx 87.7 \mathrm{~kJ}

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