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Question
A fully charged mobile phone with a 12 V battery is good for a 10 minutes talk-time. Assume that, during the talk-time the battery delivers a constant current of 2 A and its voltage drops linearly from 12 V to 10 V as shown in the figure. How much energy does the battery during this talk-time?
A fully charged mobile phone with a 12 V battery is good for a 10 minutes talk-time. Assume that, during the talk-time the battery delivers a constant current of 2 A and its voltage drops linearly from 12 V to 10 V as shown in the figure. How much energy does the battery during this talk-time?
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Solution
The correct option is C 13.2 kJ
P = VI
Energy = P . t = V . It = (V.t)I
I = 2A (given)
V . t = Area under V - t curve
V.t=(12×2×600)+(10×600)
= 600 + 6000
V . t = 6600
E = (6600) × 2 = 13200 = 13.2 kJ
P = VI
Energy = P . t = V . It = (V.t)I
I = 2A (given)
V . t = Area under V - t curve
V.t=(12×2×600)+(10×600)
= 600 + 6000
V . t = 6600
E = (6600) × 2 = 13200 = 13.2 kJ
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