Current and Resistance

• Alessandro Volta

  • Italian Physicist
  • pioneer of electricity and power
  • credited as the inventor of electric battery
  • invented the voltaic pile in 1799
• Components of Voltaic Pile

  • copper
  • card board
  • zinc
• Battery

  • device that converts chemical energy into electrical energy
• Current

  • any motion of charge from one region to another
  • the rate (time) at which electric (quantity) charges pass through a conductor
  • symbol: I
  • SI unit for current is Ampere (A)
• Resistance

  • ratio of the voltage applied to the electric current which flows through it
  • symbol: R
  • unit: ohm (Ω)
• Georg Simon Ohm

  • German physicist
  • investigated the relationship between current and voltage
  • resistance did not change with voltage
• Resistor

  • a passive electrical component that creates resistance in the flow of electrical current
• Resistivity

  • a property that describes the extent to which a material opposes the flow of electric current through it
  • acts as a constant proportionality for the relationship at resistance to the length.
• • resistance increase with temperature
  • the more area of cross section of the wire, the less is the resistance.
  • the less the area, the more the resistance
  • as the length increases, the resistance increases
• Ohm's Law

  • the voltage across a conductor is directly proportional to the current flowing through it, given a constant resistance.
• Ohmic Material

  • substances that obey ohm's law
  • the relationship between the voltage applied across it and the current passing through its linear
• Non-Ohmic Material

  • substances that does not obey ohm's law
  • the relationship between voltage and current in non-ohmic is not linear
• Dielectric

  • an electrical insulating material that can be placed between the plates of a capacitor
  • used to store energy by creating an electric field within the material