Question

A rechargeable flashlight battery is capable of delivering 90 mA for about 12 h. How much charge can it release at that rate? If its terminal voltage is 1.5 V, how much energy can the battery deliver?

Answer 1

Explanation:

It is given that,

Current, $I=90\ mA=90\times 10^{-3}\ A$

Time taken, t = 12 h = 43200 s

(a) We need to find the charge released. Current flowing is given by :

$I=\dfrac{q}{t}$

$q=I\times t$

$q=90\times 10^{-3}\times 43200$

q = 3888 C

(b) Terminal voltage, V = 1.5 V

Energy delivered is given by :

$W=E=V\times q$

$E=1.5\ V\times 3888\ C$

E = 5832 Joules

Hence, this is the required solution.