Electricity

Required for Current

• Free charges that can move
• Medium to support current
  • Vacuum counts
• Potential difference

Definitions

Voltage

• Conventional current flows from higher voltage to lower voltage

Power

• Electric power, like mechanical power, is the rate of doing work, measured in watts $P = work\space done\space per\space unit\space time=\frac{VQ}{t}=VI=I^2R=\frac{V^2}{R}$

Loads

Passive

• Charges move through PD from high to low
  • Work is done by charges on device
• Potential energy of the charges due to voltage between terminals
  • Converted to kinetic energy

Sources

Active

• Charges move through device from low to high
  • Work done on charge
• Energy converted to electric potential from other type
  • Mechanical
  • Chemical
• Generators
• Batteries