The emf of a storage battery is 90 V before charging and 100 V after charging by a direct current voltage supply. When charging began the current was 10 A. What is the current at the end of charging if the internal resistance of the storage battery during the whole process of charging may be taken as constant and equal to 2 ohms?

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A battery is charged at a potential of 15 V for 8 h when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 h. The mean terminal voltage during discharge is 14 V. The watt-hour efficiency of the battery is

The correct option is D 87.5%Energy effeciency= Energy outputEnergy input Where, Energy = voltage × current× time so, η=14×5×1515×10×8η=78 = 87.5 %

A battery is charged at a potential of $15 V$ for $8 h$ when the current flowing is $10 A$ . The battery on discharge supplies a current of $5 A$ for $15 h$ . The mean terminal voltage during discharge is $14 V$ . The watt-hour efficiency of the battery is

The correct option is D $87.5 %$
Energy effeciency= $\frac{E n e r g y o u t p u t}{E n e r g y i n p u t}$
Where, Energy = voltage $\times$ current $\times$ time
so, $η = \frac{14 \times 5 \times 15}{15 \times 10 \times 8} η = \frac{7}{8}$
$= 87.5$ %