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Q & A: Ohm's law still okay

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Most recent answer: 10/22/2007
Q:
According to Ohmís Law V is directly proportional to I. But according to relation P=VI V becomes inversely propotional to I. Does this mean that Ohmís Law is false or is there some explanation. Could you please explain. Thanks.
- Nimish (age 15)
India
A:

Ohm’s law states that  V = R * I where V is a voltage, R is a resistance and I is a current.
The relation P = V * I says that the power, P, is proportional to the voltage times the current.
If you do the algebra you find that P = V^2 / R  or, equivalently  P = I^2 * R.  No problem here with Ohm’s law.

LeeH


(published on 10/22/2007)

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