Ohms Law Calculator

Ohms Law Calculator

Enter any two known values and press "Calculate" to solve for the others. For example, a 100 watt light bulb operating on 120 volts AC will have 144 ohms of resistance and will draw 0.833 Amps. Enter 100 in the Watts field and 120 in the Voltage field and press Calculate to find the resistance and current. Fields should be reset to 0 before each new calculation.

Voltage (E) = Current (I) * Resistance (R)
Power (watts) = Current Squared (I^2) * Resistance (R)
Power = I*E = E^2 / R

Volts (E)
Amps (I)
Ohms (R)
Power (Watts)

Ohm's Law

Ohm's Law defines the relationships between (P) power, (E) voltage, (I) current, and (R) resistance. One ohm is the resistance value through which one volt will maintain a current of one ampere.

( I ) Current is what flows on a wire or conductor like water flowing down a river. Current flows from points of high voltage to points of low voltage on the surface of a conductor. Current is measured in (A) amperes or amps.

( E ) Voltage is the difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit, and is measured in (V) volts.

( R ) Resistance determines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistance allows a small amount of current to flow. A very low resistance allows a large amount of current to flow. Resistance is measured in ohms.

( P ) Power is the amount of current times the voltage level at a given point measured in wattage or watts.

Voltage Resistance Amperage or Current Power E times I = P I squared times R = P E squared divided by R = P square root of (P times R) = E P divided by R = E I times R = E E divided by I = P E squared divided by P = R P divided by ( I squared ) = R square root of ( P divided by R ) = I P divided by E = I E divided by R = I Ohm's Law  

Ohm's Law: Calculators

Before clicking for the answer, enter numbers into the equation you wish to use to calculate for Current, Power, Resistance, or Voltage.

Current (I)
Power (P)
Resistance (R)
Voltage (E)
Ohm's Law Pie Chart

Calculate for Current (I)
Power Voltage Current
Watts Volts Amps
Power Resistance Current
Watts Ohms Amps
Voltage Resistance Current
Volts Ohms Amps

Calculate for Power (P)
Current Resistance Power
Amps Ohms Watts
Voltage Current Power
Voltage Resistance Power

Calculate for Resistance (R)
PowerCurrent Resistance
VoltageCurrent Resistance
VoltagePower Resistance

Calculate for Voltage (E)
CurrentResistance Voltage
PowerCurrent Voltage
PowerResistance Voltage

Ohm's Law Pie Chart

GW1NGL NA7KR Kevin Roberts Ham Radio

Page last updated on 09/10/2012 by Kevin Roberts NA7KR a colection of Ham Radio and Electronic Information