Final answer:
Variable resistance is a changeable value that controls current in a circuit, closely related to Ohm's law, which defines the relationship between voltage, current, and resistance.
Step-by-step explanation:
Variable resistance refers to a component or material whose resistance value can be changed, usually to control the current flowing in a circuit. The principle correlated to variable resistance is Ohm's law, which describes the relationship between voltage (the cause), current (the effect), and resistance. Ohm's law is formulated as V = IR, where V is voltage, I is current, and R is resistance. According to Ohm's law, if you increase the resistance while keeping the voltage constant, the current decreases. Conversely, if you decrease the resistance, the current increases. Variable resistors or potentiometers are common examples of devices that provide variable resistance.
Another factor associated with resistance is the material properties, which include resistivity, length of the conductor, and its cross-sectional area. In certain materials, resistance is not a constant value but varies with temperature, as resistivity is affected by changes in temperature. This effect can cause a deviation from Ohm's law at higher currents due to heating, which is particularly notable in non-ohmic materials.