# Q & A: Watts and Volts

Q:
How do you convert watts to volts.
- Trevor
A:
You can't.

A Watt is a unit of electrical power, which expresses how much energy (measured in Joules) gets used or transmitted per second. A Volt is a measure of electric potential. It expresses how much energy you get per unit charge, with no mention of time.

1 Watt = 1 Joule/Second
1 Volt = 1 Joule/Coulomb

(a Coulomb is a unit of electrical charge).

If you happen to know the current flowing through something, measured in Amperes (affectionately called "Amps"):

1 Ampere = 1 Coulomb/Second

you can figure out how many Watts of energy are used if you know also the voltage:

1 Watt = 1 Ampere * 1 Volt

So you need to know two things in order to figure out the third.

It's a lot like asking how to convert miles into hours. You need to know speed too!

Tom

(published on 10/22/2007)

## Follow-Up #1: Volts to Watts?

Q:
So what would the answerbe to this problem (if you know the answer) 0.004 volts = how many watts?
- Katie (age 15)
Canton, OH, USA
A: