Question

A typical cell phone consumes an average of about 1.00 W of electrical power and operates on 3.80 V. (a) What average current does the phone draw from its battery? (b) Calculate the energy stored in a fully charged battery if the phone requires charging after 5.00 hours of use.

Answer 1

Answer:

0.06925 A

18000 J

Explanation:

V = Voltage = 3.8 V

P = Power = 1 W

t = Time = 5 hours

Power is given by

$P=V^2I\\\Rightarrow I=\dfrac{P}{V^2}\\\Rightarrow I=\dfrac{1}{3.8^2}\\\Rightarrow I=0.06925\ A$

The average current the phone draws from its battery is 0.06925 A

Energy is given

$E=Pt\\\Rightarrow E=1\times 5\times 3600\\\Rightarrow E=18000\ J$

The energy stored in a fully charged battery is 18000 J