Resistance
Resistance Resistance is the opposition that a substance offers to the flow of electric current. It is represented by the uppercase letter R. Formula R is the resistance in ohms (Ω). ρ is the resistivity in ohms-meter (Ω×m) l is the length of the conductor in meter (m) A is the cross sectional area of the conductor. The standard unit of resistance is the ohm. Ohms are named after Georg Simon Ohm (1784-1854), a German physicist who studied the relationship between voltage, current and resistance. Symbolized by the uppercase Greek letter omega: Resistance of resistors in series The total equivalent resistance of resistors in series is the sum of the resistance values: R Total = R 1 + R 2 + R 3 +... Resistance of resistors in parallel The total equivalent resistance of resistors in parallel is given by: ...