Watts Amps Volts
Watts, Amps, Volts, Ohms


About sixty people a day visit this metric web site asking for a conversion from watts to volts or an amp to volt conversion. It is not really a conversion as such but a formula where any two values are needed to be known to enable the third to be calculated.

I remember the formula as WAV (wave; hi there!) - Watts = Amps x Volts

By dividing both sides of the formula by amps you get - Watts / Amps = Volts
... the amps / amps on the right hand side canceling each other out to leave volts.

and by dividing both sides by volts you get - Watts / Volts = Amps
... the volts / volts on the right hand side canceling each other out to leave amps.


q. What is the biggest electric fire that can be run on a 13 amp fused plug in the UK?

a. Mains voltage in the UK is 230v so Watts = 13 x 230 = 2990 watts or just under 3kW

q. A 60 watt car spotlight is showing a drain of 5.5 amps on the ammeter.
    What is the voltage?
a. 60 / 5.5 = 10.9 volts

q. A food mixer with a 400 watt motor runs in the US on 120 volt supply.
    What fuse to fit?
a. 400 / 120 = 3.33 amps. A 5 amp fuse would be ok.

Ohms is a measure of resistance and Ohms = Volts / Amps

This is keeping it simple - for more info see other web sites like ebtx.com

Watts may be converted directly to energy units such as Btu/hr, Calories/hr, horsepower, tons refrigeration and Joules - see the main conversion tables...


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last modified : 11th September 2011

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