Resistance is a measure of the opposition to current flow in an electrical circuit. Resistance is measured in ohms, symbolized by the Greek letter omega (Ω). Insulators: Materials that present high resistance and restrict the flow of electrons.

the current through a conductor between two points is directly proportional to the voltage across the two points.

Resistance is the tendency for materials to oppose the flow of electric charges. Resistance occurs when electric charges flow through wires at great speed.

(Entry 1 of 2) : the practical meter-kilogram-second unit of electric resistance equal to the resistance of a circuit in which a potential difference of one volt produces a current of one ampere.

Objects made of electrical insulators like rubber tend to have very high resistance and low conductivity, while objects made of electrical conductors like metals tend to have very low resistance and high conductivity. This relationship is quantified by resistivity or conductivity.

Metals such as copper typify conductors, while most non-metallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them. “Conductor” implies that the outer electrons of the atoms are loosely bound and free to move through the material.

In the open circuit the current can not flow from one end of the power source to the other. Because of this there is no current flow, and therefore the light does not turn on.

Current is the change in charge over the change in time. Resistance is proportional to resistivity and length, and inversely proportional to cross sectional area.

The resistance of a cylindrical segment of a conductor is equal to the resistivity of the material times the length divided by the area: R≡VI=ρLA. The unit of resistance is the ohm, Ω. For a given voltage, the higher the resistance, the lower the current.