Question

A 12.0 V car battery is being used to power the headlights of a car. Each of the two headlights has a power rating of 37.7 Watts. The number of electrons that pass through the car battery each second is ___ x 1019. Assume three significant digits in your answer. You do not need to use scientific notation when you enter your answer.

Answer 1

3.921*10^19 electrons

Step-by-step explanation:

To find the number of electron that trough the car battery you first calculate the current by using the following formula, which relates the power with the voltage:

`P=IV` (1)

P: power of both headlights = 2(37.7W) = 75.4 W

I: current = ?

V: voltage of the battery = 12.0 V

You solve the equation (1) for I:

`I=(P)/(V)=(75.4W)/(12.0V)=6.283A=6.238(C)/(s)`

Next, you use the equivalence 1C = 6.241*10^18 electrons:

`6.238(C)/(s)*(6.241*10^(18)\ electrons)/(1C)=3.921*10^(19)\ electrons/s`

The number of electrons that cross the battery per second is 3.921*10^19 electrons