## Resistance
### The electrical resistance of an object is a measure of its opposition to the passage of a electric current. An object of uniform cross section will have a resistance proportional to its resistivity and in length and inversely proportional to its cross sectional area. Discovered by Greg Ohm in 1827, electrical resistance share some conceptual parallels with the mechanical notion of friction. The SI unit of electrical resistance is ohm. Resistance reciprocal quality is electrical conductance measured in siemens. The resistance of an object can be defined as the ratio of voltage to current.
Resistance of a resistor is computed by dividing the voltage across the resistor by the current flowing through it. The unit of measurement for resistance is the ohm. The ohm is defined as the amount of resistance that produces 1 ampere of current flow when 1 volt is applied. The symbol for resistance is R
For many types of electrical devices, and most resistors, the resistance is independent of the applied voltage. In other words, a the resistance of a resistor will not change when the voltage applied to it changes. When the resistance is independent of the applied voltage, the following law holds.
## Resistance in Series
Two single voice coil 4 ohm wire in series will produce a 8 ohm resistance or "load" presented to the amplifier.
## Resistance in Parallel
Two single voice coil 8 ohm wire in parallel will produce a 2 ohm resistance or "load" presented to the amplifier.
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