A CDE Definition
The unit of measurement of electrical resistance in a material. One ohm is the resistance in a circuit when one volt maintains a current of one amp. The symbol for ohm is the Greek letter omega. See impedance.
The equation "R=V/I" is the more streamlined version of the one developed by German physicist Georg Simon Ohm in 1827. Ohm's law is used to calculate the resistance in materials such as metal, which maintain a linear relationship between voltage and current. In addition, Ohm's formulas, which are derived from Ohm's Law, are used to calculate voltage and current if the other two measurements are known.
Resistance = voltage divided by current
R = V / I or R = E / I
Voltage = current times resistance
V = I * R or E = I * R
Current = voltage divided by resistance
I = V / R or I = E / R
V or E = voltage (E=energy)
I = current in amps (I=intensity)
R = resistance in ohms
Power in watts = voltage times current
P = V * I
(1) The opposition to the flow of alternating current in a circuit. Represented by the letter "Z" and measured in ohms, impedance is the combination of resistance, inductance and capacitance of the circuit. See ohm.
(2) The opposition that a speaker produces to the alternating current coming from an amplifier. The lower the impedance, the more power required. Most speakers have an impedance of four to eight ohms. See ohm.
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