Difference between revisions of "Ohm's Law"
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| − | '''Ohm's law''' is a mathematical relationship of three variables in an electronic [[circuit]] containing a resistive element. It states that the voltage across a resistive element is equal to the [[current]] passing through the resistive element times the [[resistance]] of the resistive element. | + | '''Ohm's law''' is a mathematical relationship of three variables in an electronic [[circuit]] containing a resistive element. It states that the voltage across a resistive element is equal to the [[current]] passing through the resistive element times the [[resistance]] of the resistive element. |
In mathematical terms, this is written as: | In mathematical terms, this is written as: | ||
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:I: Current through resistive element | :I: Current through resistive element | ||
:R: Resistance of resistive element | :R: Resistance of resistive element | ||
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| + | In this equation, R is always constant, regardless of the current and voltage. In real life, however, the temperature of a resistor will rise as the current through it increases. Since resistance and temperature are positively correlated, Ohm's law becomes only an approximation (and sometimes a very bad approximation) when the resistive element heats up. For example, an incandescent light bulb does not follow Ohm's law because it becomes hot very rapidly when a current is applied. | ||
[[Category:Mathematics]] | [[Category:Mathematics]] | ||
[[Category:Physics]] | [[Category:Physics]] | ||
[[Category:Electrical Engineering]] | [[Category:Electrical Engineering]] | ||
Revision as of 17:42, November 19, 2009
Ohm's law is a mathematical relationship of three variables in an electronic circuit containing a resistive element. It states that the voltage across a resistive element is equal to the current passing through the resistive element times the resistance of the resistive element.
In mathematical terms, this is written as:
- <math>V = I*R</math>
Where
- V: Voltage across resistive element
- I: Current through resistive element
- R: Resistance of resistive element
In this equation, R is always constant, regardless of the current and voltage. In real life, however, the temperature of a resistor will rise as the current through it increases. Since resistance and temperature are positively correlated, Ohm's law becomes only an approximation (and sometimes a very bad approximation) when the resistive element heats up. For example, an incandescent light bulb does not follow Ohm's law because it becomes hot very rapidly when a current is applied.