- #1

Inertialforce

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## Homework Statement

A 12V battery from a car is used to operate a 65W headlight.

a)How much energy does the headlight use in 1.5 hours?

b)What total charge passes through the headlight during this time?

c)What is the total number of electrons that pass through the headlight during this time period?

## Homework Equations

P = IV

## The Attempt at a Solution

What I did for question "a" is, I realized that the voltage going through the entire circuit (in this case) was 12V and I also knew that the headlight had a "P" of 65W. So what I did was I used the equation P= IV and isolated for I to get the current, since current is measured in Amps or

**coulombs/sec**. So knowing this fact I calculated it out and came up with an answer of 5.4 coulombs/sec for the current.

Now my question is how do I use that 1.5 hours in my calculations? Do I just multiply it to the 5.4 coulombs/sec answer that I got (from isolating the current in the equation P= IV), which would cancel out the unit seconds and leave me with the unit of coulombs?