Metals typically have many free electrons, and are good conductors. In insulators, electrons cannot easily move freely, so they are not readily available for electric current.
For electric current to flow, the electrons need a complete pathway, or circuit. To make them move, there must be a force. It is called electromotive force, also known as voltage.
Semiconductors are widely useful because their conductivity can be manipulated and precisely controlled – by such means as introducing impurities, or an electric field, or just light.
Ohms Law states that: I = V/R where I is the current in amperes, V is the potential difference in volts, and R is a resistance, measured in ohms. Ohm's Law gives an accurate method of determining values in an electrical circuit.
Electrical power is a measurement of output, or the rate of work. If an electrical component has a rating in Watts, it will be a measurement of power consumption. To calculate power: P = I x E or Watts = Amps x Volts.
