# Ohm's Law

Ohm's Law is the relationships between power \((P)\), voltage \((V)\), current \((I)\), and resistance \((R)\).

## OHM'S LAW PIE CHART

## Voltage (Volt)

Volt \(\:(V)\:\) or \(\:(E)\:\) is a unit of electrical pressure. One volt is the amount of pressure that will cause one ampere of current in one ohm of resistance. Different voltages that are typically used in the oilfield in the USA are 480V, 4,160V and 12kV (Kilo Volt)

### Voltage formulas

\(\large{ Volts = \sqrt{Watts \; Ohms} = V = \sqrt{P \; R} }\) | |

\(\large{ Volts = \frac{Watts}{Amps} = V = \frac{P}{I} }\) | |

\(\large{ Volts = Amps \; Ohms = V = I \; R }\) |

## Current (Amp)

Current \(\:(I)\:\) is the rate of flow of electricity in a circuit, measured in amperes.

Amp is a unit of current. One ampere (amp) is the current flowing through one ohm of resistance at one volt potential.

### Current formulas

\(\large{ Amps = \frac{Volts}{Ohms} = I = \frac{V}{R} }\) | |

\(\large{ Amps = \frac{Watts}{Volts} = I = \frac{P}{V} }\) | |

\(\large{ Amps = \sqrt{\frac{Watts}{Ohms}} = I = \sqrt{\frac{P}{R}} }\) |

## Power (Watt)

Power \(\:(P)\:\) is the rate of doing work and is measured by the amount of foot pounds of work done in a particular unit of time. A horsepower is a measure of power.

### Power formulas

\(\large{ Watts = \frac{Volts^2}{Ohms} = P = \frac{V^2}{R} }\) | |

\(\large{ Watts = Volts^2 \; Ohms = P = V^2 \; R }\) | |

\(\large{ Watts = Volts \; Amps = P = V \; I }\) |

## Resistance (Ohm)

Resistance \(\:(R)\:\) is the ability to resist or prevent the flow of current. In order to overcome the resistance and get the current to flow a higher voltage will be required. Resistance is measured in Ohms, represented by \(R\) and has a symbols \(\Omega\).

Ohm is a unit of resistance. A constant current of one ampere produces a force of one volt.

### Resistance formulas

\(\large{ Ohms = \frac{Volts}{Amps} = R = \frac{V}{I} }\) | |

\(\large{ Ohms = \frac{Volts^2}{Watts} = R = \frac{V^2}{P} }\) | |

\(\large{ Ohms = \frac{Watts}{Amps^2} = R = \frac{P}{I^2} }\) |

## electrical symbols

Quantity | Symbol | Measuring Units | Description |
---|---|---|---|

Capacitance | \(C\) | Farad | unit of capacitance
\(C=Q + V\) |

Charge | \(Q\) | Coulomb | unit of electrical charge
\(Q=C \; V\) |

Conductance | \(G\;\) | Siemen | reciprocal of resistance
\(G=1+R\) |

Current | \(I\) | Amp | unit of electrical current
\(I= \frac{V}{R}\) |

Frequency | \(Hz\) | Hertz | unit of frequency
\(f=1 + T\) |

Impedance | \(Z\) | Ohm | unit of AC resistance
\(Z^2=R^2 + X^2\) |

Inductance | \(L\;\) or \(\;H\) | Volt | unit of inductance
\(V_L=L \frac{di}{dt} \) |

Power | \(P\) | Watt | unit of power
\(P=V \; I\) |

Resistance | \(R\) or \(\Omega\) | Ohm | unit of DC resistance
\(R=V+I\) |

Voltage | \(V\;\) or \(\;E\) | Volt | unit of electrical potential
\(V=I \; R\) |

Tags: Equations for Electrical Equations for Cathodic Protection