130 volt lamp

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drwill

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If a lamp is rated at 100 watts at 130 volts. what is that same lamp put out in watts if supplied at 120 volts.

just wanted to know if my math was correct.
P.S. I come up with 85 watts

Thanks drwill
 
Re: 130 volt lamp

drwill,

The math is right, but note that the resistance of the filament in a light bulb is highly dependent on temperature, so I don't know what the actual output will be, but it should be close.

To see this, measure the resistance of the light bulb. I have a cold light bulb, 100w, 120v. The resistance is 10 ohms. But when it is on... R=E^2/P, so R = 120v^2/100w = 144 ohms!

[ April 23, 2005, 03:19 PM: Message edited by: sirdle ]
 
Re: 130 volt lamp

Because the filament resistance and therefore current is temperature dependant the easiest way to find the answer is to measure it. I'd measure the current and deduce the resistance. Rather than measure the resistance and deduce the current.

I've got some physics equations that solve for heat dissipation in calories, I've never used them.
 
Re: 130 volt lamp

Now Sam, don't get physical with us!

It should be a simple matter to measure the current with an Amprobe.

The 130V lamp is a cheap substitute for over priced long life lamps, but I haven't found anything to survive the dropping of a trouble light!
 
Re: 130 volt lamp

Hey, Rattus, where ya been, haven't seen ya in a little while.

And isn't that what I said? :p
 
Re: 130 volt lamp

Sam, thatis exactly what you said. "That's a joke son! Pay attention boy!"

Been trying to think up a nasty test question--something to outdo the Oregon Fudge Factor.

Got any ideas?
 
Re: 130 volt lamp

Charlie, I think it was Henery with two e's. You gotta admire his spunk however you spell it.
 
Re: 130 volt lamp

Please. Looney Tunes didn't become anti-PC until well into the 90's. :D

foghorn0027.jpg
 
Re: 130 volt lamp

How bout Baby Huey?
huey.gif
First appeared 1949.

[ April 24, 2005, 07:09 PM: Message edited by: physis ]
 
Re: 130 volt lamp

looks like I need to request a new forum on
Adult attention deficit disorder


just kidding guys

drwill
 
Re: 130 volt lamp

By Rattus:

Been trying to think up a nasty test question
Click to expand...
Why not the one I eluded to? Calculating heat dissipation in calories. I'll start a thread for you.
 
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