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Details
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Voltage
[V] |
The measure of the power differental between two points. It is the electromotive force. This is measured in volts [V]. |
Current Iintensity
[I] |
The flow of electric charge across a surface. This is measured in amps [A]. |
Power
[P] |
The rate of energy transfer. This is measured in ['watts'] [W]. |
Resistance
[R] |
The rate of energy transfer. This is measured in ohms [Ω]. |
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Formulas
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| To find |
Known |
Formula |
| Volts |
Amps [I]
Resistance Ω
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V = I x R
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| Volts |
Watts [P]
Amps [I]
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V = P⁄I
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| Volts |
Watts [P]
Resistance Ω
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√ P x R
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Amps [I]
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Volts
Resistance Ω
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I = V⁄R
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Amps [I]
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Watts [P]
Volts
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I = P⁄ V
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Amps [I]
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Watts [P]
Resistance Ω
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I = √ P⁄R
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Watts [P]
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Volts
Amps [I]
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P = V x I |
Watts [P]
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Volts
Resistance Ω
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P = V2⁄R |
Watts [P]
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Amps [I]
Resistance Ω
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P = I2 x R |
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Resistance Ω
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Volts
Amps [I]
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R = V⁄I
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| Resistance Ω |
Volts
Watts [P]
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R = V2⁄P |
| Resistance Ω |
Watts [P]
Amps [I]
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R = P⁄I2 |
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Further reference:
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Revision history:
- 2020-12-02 : v1.4 - Updated code for PHP 8.0
- PHP Warning: Undefined variable $count
defined.
- PHP Warning: Undefined array key "volts"
predefined $out array.
- PHP Fatal error: Uncaught TypeError: round(): Argument #1 ($num) must be of type int|float, string given
test is_numeric()
- 2020-12-01 : v1.3 - Fixed input bug. Watts field name mangled. Fixed.
- 2020-10-25 : v1.2 - Updated PHP, to correct for warnings for lazy coding
- "Use of undefined constant amps - assumed 'amps'"
- "syntax error, unexpected '' (T_ENCAPSED_AND_WHITESPACE),"
- 2017-07-29 : v1.1 - Fixed pow bug. x^2 != x*x . Use pow(x, 2).
Added if ($debug == 1), and index output of which formula(s) were used, with actual values.
- 2017-07-28 : v1.0 - Original work.
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