Voltage and Current

Voltage is the difference of electrical potential between two points of an electrical network, expressed in volts. It is a measure of the capacity of an electric field to cause an electric current in an electrical conductor.
http://en.wikipedia.org/wiki/Voltage

Electric current is by definition the flow of electric charge. The SI unit of electric current is the ampere (A), which is equal to a flow of one coulomb of charge per second.
http://en.wikipedia.org/wiki/Electric_current

电压voltage (V) 和电流current (I) 是有以下的相互关系:-

I=V/R (Ohm's Law)

where R is resistance(电阻)