Ohm LAW (Direct Current)

At constant temperature, the potential difference (V) applied to two ends of a metal conductor is directly proportional to the intensity of the current (I) which flows through the conductor.

According to Ohm's law, if R is the resistance of the conductor, V is the potential difference at the extremes of the resistance and I is the intensity of the current: the following relationships apply.

• V = R * I (the result is in Volts)
• I = V / R (the result is in Ampere)
• P = V * I (the result is in Watts, where P is the Power)

Summary table

P = POWER (Watt)

P = V * I (W) if I replace V with R * I we will have P = R * I² if I replace I in the formula with V / R we will have P = V² / R

V = VOLTAGE (Volt)

V = R * I (Volt) if I replace I with P / V we would have V² = R * P = 

If I replace R with V / I in the formula, we will have that V = V / I * I = P / I since P = V * I

R = Resistance (OHM = Ω)

R = V / I if I replace V with P / I we will have R = P / I² if instead I replace I with P / V we will have R = V / P / V and finally       R = V² / P

I = Current (Ampere)

I = V / R if I replace R with V / I we will have V / V / I and since V * I = P we will have I = P / V; if I replace the V with R * I in the formula I = P / V we will have that: I² = P / R so:

Alternating Current (AC)

For alternating current, if we use the symbolic method (which is used when dealing with sinusoidal quantities) as it is immediate and has the characteristic of formalizing the laws of alternating current circuits, and can be considered similar to those already views for direct current circuits.

definitely, thanks to the use of symbolic notation, the relationship between current and voltage remains analogous to Ohm law in the direct current: V = R * I

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