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11 years ago
I know the voltage increases but I've been hearing that the current decreases due to the power dissipating as heat in the light bulb. This however confuses me because I am trying to infer as the current and voltage increase so does the resistance and that is what my chart/graph shows as well.
If I could get a confirmation if current increases or decreases that would be great! thanks!
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wrote...
#1
11 years ago
The answer to this question depends on what is being held constant:

The basic relations are:
V = I * R

Power = I * V

If you fix the power as Po:
Po = I * V = I^2 * R = V^2/R

Then:
I = sqrt(Po/R)

So if the power is fixed, current DECREASES with resistance.

But if voltage is fixed,
I = V/R
and current still DECREASES with resistance.

OK, so it decreases either way.
wrote...
#2
11 years ago
A light bulb can be seen as a resistor. Power is voltage times amperage (P = V x I). Power is constant. So it is impossible that voltage and amperage can both go up at the same time.

Cheers ebs
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