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Is it watt per second or watt per hour

by bionic6manuel
Tags: consume, generator, watts
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bionic6manuel
#1
Jul6-11, 04:56 PM
P: 15
Say I have a device (Thermoelectric generator) that "generates power" at 4 watts, as per watt meter reading, is it producing 4 watts a second or 4 watts an hour. I say it is producing 4 watts a second but my brother in law says 4 watts an hour so the watt meter can tell the future. Please bear in mind I am not consuming energy but generating energy.
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Dadface
#2
Jul6-11, 05:01 PM
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Hello .Watts is a unit of power(Joules per second) so the 4 Watt device is producing 4 Joules per second.

To clarify this further the Joule is a unit of energy so the device is producing 4 Joules of energy every second.
cjl
#3
Jul6-11, 05:13 PM
P: 1,029
Watts are a unit of power, so it doesn't make sense to talk about watts per hour (or per second). They already have the "per unit time" built in.

stevenb
#4
Jul6-11, 05:14 PM
P: 697
Is it watt per second or watt per hour

Quote Quote by bionic6manuel View Post
... is it producing 4 watts a second or 4 watts an hour ...
It is generating 4 Watts for as long as you leave it on.

See Dadface's answer above. Power is a measure of how fast you generate energy (or consume it). Joules is a measure of total generated energy.

Your brother may be getting confused by the units WHr which is also a measure of energy (that's Watt hours, not Watts per hour). If you leave a 4 W device running for one hour, you generate 4 WHr of energy, which is 4 JHr/s x 3600 sec / 1 Hr, which is 14400 Joules.
bionic6manuel
#5
Jul7-11, 04:39 AM
P: 15
I thank you all very much for the explanation
Pythagorean
#6
Jul7-11, 12:40 PM
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Quote Quote by cjl View Post
Watts are a unit of power, so it doesn't make sense to talk about watts per hour (or per second). They already have the "per unit time" built in.
Watts per time is the change in power over time :)


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