# Ohm's Law

on . Posted in Electrical Engineering

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

### Ohm's Law Index

Ohm's law is a fundamental principle in physics and electrical engineering that describes the relationship between voltage, current, and resistance in an electrical circuit.  It states that the current flowing through a conductor is directly proportional to the voltage applied across it and inversely proportional to the resistance of the conductor.In simpler terms, Ohm's law states that the current flowing through a conductor is equal to the voltage across it divided by the resistance.  It means that as the voltage increases, the current flowing through the conductor also increases, given that the resistance remains constant.  Conversely, if the resistance increases, the current decreases for a given voltage.

### electrical Formulas

Current Power Resistance Voltage
$$I = V \;/\; R$$ $$P = I^2 \; R$$  $$R = V \;/\; I$$ $$V = I \; R$$
$$I = \sqrt{ P \;/\; R }$$ $$P = V \; I$$ $$R = P \;/\; I^2$$ $$V = P \;/\; I$$
$$I = P \;/\; V$$ $$P = V^2 \;/\; R$$ $$R = V^2 \;/\; I$$ $$V = \sqrt{P\;R}$$

### Voltage (Volt)

Electric voltage V or E, also known as electric potential difference, is the measure of the electric potential energy per unit charge that is required to move a charge from one point to another in an electric field.  A unit of electrical pressure.  One volt is the amount of pressure that will cause one ampere of current in one ohm of resistance.

In simple terms, voltage is the force that drives the electric current through a conductor.  It is similar to the pressure that drives water through a pipe.  The greater the voltage, the more electric charge will flow through a circuit.  Voltage can be calculated using Ohm's Law, which relates voltage, current, and resistance in an electrical circuit.

### Current (Amp)

Electric current, abbreviated as I, is the flow of electric charge in a circuit or a conductor.  The current flow is caused by the movement of electrons, which are negatively charged particles, through a conductor such as a wire.  The rate of flow of electric charge (current) is typically determined by the voltage (potential difference) applied across the conductor and the resistance of the conductor.  The relationship between voltage, current, and resistance is described by Ohm's Law, which states that the current through a conductor is directly proportional to the voltage applied across it and inversely proportional to its resistance.

### Power (Watt)

Electrical power, abbreviated as P, is the rate at which electrical energy is transferred or converted into other forms of energy, such as mechanical or thermal energy.  The power delivered by an electrical circuit is equal to the product of the voltage (V) and the current (I) flowing through the circuit.  This relationship is known as Joule's Law.  Electrical power can be calculated using various other formulas depending on the specific circumstances, such as the use of AC or DC power, reactive power, or power factor.

### Resistance (Ohm)

Electric resistance R is a measure of how much an object or substance opposes the flow of electric current through it.  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 $$\Omega$$.  The resistance of an object depends on its size, shape, material, and temperature.  The resistance of a material can be calculated using Ohm's Law, which states that the current flowing through a conductor is directly proportional to the voltage across it, and inversely proportional to its resistance.

### electrical symbols

Quantity Symbol Unit Formula
Capacitance $$C$$ Farad $$C= Q\;/\;V$$
Charge $$Q$$ Coulomb $$Q= I \; t$$
Conductance $$G$$ Siemen $$G=P\;/\;V^2$$
Current $$I$$ Ampere $$I= V\;/\;R$$
Frequency $$Hz$$ Hertz $$f=1 + T$$
Impedance $$Z$$ Ohm $$Z=\sqrt{R^2 + (X_L - X_C)^2}$$
Inductance $$L\;$$ or $$\;H$$ Henry $$L = \mu \; n^2 \;A\;/\;l$$
Power $$P$$ Watt $$P=V \; I$$
Resistance $$R\;$$ or $$\;\Omega$$ Ohm $$R=V\;/\;I$$
Voltage $$V\;$$ or $$\;E$$ Volt $$V=I \; R$$

### electrical Units (Multipliers and Submultipliers)

Prefix Symbol Multiplier Power of Ten
yotto Y $$1,000,000,000,000,000,000,000,000$$ $$10^{24}$$
zetta Z $$1,000,000,000,000,000,000,000$$ $$10^{21}$$
exa E $$1,000,000,000,000,000,000$$ $$10^{18}$$
peta P $$1,000,000,000,000,000$$ $$10^{15}$$
tera T $$1,000,000,000,000$$ $$10^{12}$$
giga G $$1,000,000,000$$ $$10^{9}$$
mega M $$1,000,000$$ $$10^{6}$$
kilo k $$1,000$$ $$10^{3}$$
hecto h $$100$$ $$10^{2}$$
deca da $$10$$ $$10^{1}$$
none none $$1$$ $$10^{0}$$
deci d $$1\;/\;10$$ $$10^{-1}$$
centi c $$1\;/\;100$$ $$10^{-2}$$
milli m $$1\;/\;1,000$$ $$10^{-3}$$
micro $$\mu$$ $$1\;/\;1,000,000$$ $$10^{-6}$$
nano n $$1\;/\;1,000,000,000$$ $$10^{-9}$$
pico p $$1\;/\;1,000,000,000,000$$ $$10^{-12}$$
femto f $$1\;/\;1,000,000,000,000,000$$  $$10^{-15}$$
atto a $$1\;/\;1,000,000,000,000,000,000$$ $$10^{-18}$$
zepto z $$1\;/\;1,000,000,000,000,000,000,000$$ $$10^{-21}$$
yocto y $$1\;/\;1,000,000,000,000,000,000,000,000$$  $$10^{-24}$$