To determine the current (Amps) from a known voltage, you need one of two additional values: Power (Watts) or Resistance (Ohms).
Calculation Using Power
According to Watt’s Law, the current I is equal to the power P divided by the voltage V. This formula is commonly used when you know the wattage rating of a device.
I = P / V
Calculation Using Resistance
Based on Ohm’s Law, the current I is equal to the voltage V divided by the resistance R. This is the standard method for calculating load in a circuit with a known resistor.
I = V / R
Where:
- I = Current measured in Amperes (A)
- V = Potential difference measured in Volts (V)
- P = Power measured in Watts (W)
- R = Electrical resistance measured in Ohms (Ω)