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Old 01-16-09, 02:04 PM   #27
jwxr7
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Quote:
Originally Posted by MetroMPG View Post
I never thought of checking the bulb: so I just did, and it says 25w.

It blew out at 8v, which works out to 3.1 amps.
Don't sell yourself short .
The wattage of a fixed resistance like a bulb, isn't constant when voltage changes.

If it's 25w at 6 volts, that means It draws 4.2 amps (25w/6v) at 6v, so the resistance is around 1.4 ohms (6v/4.2A). Use this resistance to find the current at 8 volts. It comes out to 5.7 amps (8v/1.4ohms), so it ends up being around 45w at 8 volts (8v x 5.7).
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