Calculating the Wattage Usage of a 60-Watt Light Bulb in Three Hours

[marshall4]

How may watts does a 60-watt light bulb use in three hours?

60*3=180watts?

 

[Njorl]

Watts are a measure of power. Power is a rate of energy usage. "How many watts used in an hour?", is a nonsensical question.

Sensible questions would be:

-How many kilowatt-hours does a 60 watt bulb use in 3 hours?

-How many joules does a 60 watt bulb use in 3 hours?

Keeping in mind that a watt is 1 joule per second.


Njorl

 

[marshall4]

How many kilowatt-hours does a 60 watt bulb use in 3 hours?

how can i convert that to amps?

 

[Njorl]

Originally posted by marshall4
How many kilowatt-hours does a 60 watt bulb use in 3 hours?

how can i convert that to amps?

0.18

You can't.

 

[chroot]

60 watts for 3 hours is 60 * 3 = 180 watt-hours. That's the same as 0.180 kilowatt-hours.

Your next question, "how do I convert that [kilowatt-hours] into amps?" is as non-sensical as the first question.

- Warren

 

[FZ+]

how can i convert that to amps?

Amps = unit of current = rate of change of charge.

Volts = unit of electric potential

Joules = unit of energy.

Watt = unit of power = rate of change of energy

Kilowatt-Hours = Non-SI unit of energy

You cannot calculate current from power unless you know the voltage, or the resistance.

 

[marshall4]

ya, I'm confused

 

[ShawnD]

Watts and amps are both rates. They both stay constant and do not change with time.

To find the amps, divide by the watts by 120.

 

[FZ+]

They both stay constant and do not change with time.

Uh... hmm. This is true (as a simplification) in this case, but is not always true.

To find the amps, divide by the watts by 120.

Not neccessarily. Depends on the country.