Resistance:

Now which we have discussed the concepts of current and voltage, we are ready to describes a third key concept known as resistance. A Resistance is defined as the opposition to current flow.  The amount of opposition to current flow generate through a material depends upon the amount of available free electrons it holds and the types of obstacles the electrons encounter as they attempt to move by the material.  It is measured in ohms and is represented by the symbol (R) in equations.   A single ohm is defined as which amount of resistance which will limit the current in a conductor to one ampere whenever the potential difference (voltage) applied to the conductor is one volt.  The shorthand notation for ohm is the Greek letter capital omega (?). Current flows if a voltage is applied to a conductor.  The amount of current flow depends upon the resistance of the conductor.  The lower the resistance, the higher the current flow for provides amount of voltage. As the resistance higher the current flow the lower.