Is it watt per second or watt per hour

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Discussion Overview

The discussion centers around the interpretation of the unit "watt" in the context of a thermoelectric generator producing power. Participants explore whether the generator's output of 4 watts should be understood as 4 watts per second or 4 watts per hour, particularly in the context of energy generation versus consumption.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asserts that the device is producing 4 watts per second, emphasizing that watts are a measure of power (Joules per second).
  • Another participant clarifies that watts are inherently a unit of power and thus do not require additional time units like "per hour" or "per second." They suggest that the device generates 4 Joules of energy every second.
  • A different participant points out that discussing watts per hour does not make sense, as watts already incorporate a time component.
  • One participant mentions that the confusion may stem from the term "Watt hours," which is a measure of energy, not power, and explains how to convert the power output into energy over time.
  • Another participant reiterates that watts are a unit of power and that discussing watts per hour or per second is not meaningful.

Areas of Agreement / Disagreement

Participants generally agree that watts are a unit of power and do not require additional time units for clarification. However, there is some disagreement regarding the interpretation of the brother-in-law's statement about watts per hour.

Contextual Notes

Some participants note the potential confusion between power (watts) and energy (Watt hours), highlighting the importance of understanding the definitions and relationships between these units.

Who May Find This Useful

This discussion may be useful for individuals interested in understanding the concepts of power and energy, particularly in the context of electrical devices and measurements.

bionic6manuel
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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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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.
 
Last edited:
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.
 
bionic6manuel said:
... 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. :rolleyes:

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.
 
I thank you all very much for the explanation
 
cjl said:
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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