Electricity

• ELECTRICAL CHARGE (Q):

  A circuit works when CHARGE is allowed to FLOW through it. Usually these charges are free moving ELECTRONS or IONS.

  • A measure of total current that flowed within a period of time.
  • Units: COULOMBS (C)
• ELECTRIC CURRENT (I):

  rate of flow of charge passing through a point in one sec

  • A characteristics of current in a single closed loop is that it has the  SAME VALUE at any point in the loop.
  • Units: AMPERES (A)
• POTENTIAL DIFFERENCE (VOLTAGE):

  The measure of ENERGY per unit of CHARGE, transferred between two points in a circuit.

  • the force driving the flow of electrons around the circuit
  • provided by the cell / battery
  • Units: VOLTS (V)
• RESISTANCE (R):

  In a circuit, it SLOWS down the flow of CURRENT.

  • The HIGHER the resistance in a circuit, the LOWER the current, if the potential difference stays the same.
  • Units: OHMS (Ω)
• OHM'S LAW:

  The relationship between current, resistance & potential difference.

  • It states that the CURRENT is DIRECTLY PROPORTIONAL to the potential difference.
• OHMIC CONDUCTOR:

  A conductor that obeys ohm's law.
• circuit

  a closed loop that contains a power source & wire for the electrons to flow through

  
• electrons travel from the negative terminal to the positive terminal in a circuit

  
• conventional current

  where the electrons flow from: Positive terminal ➔ negative terminal

  • this was people used to believe in

  
• resistance is caused by the repeated collisions between the electrons in the material with each other & with the fixed positive ions in the material

  • the resistance of a component is the ratio of PD to current
• current in inversely proportional to resistance

  • more resistance = less current
  • less resistance = more current
• more:

  • length of the wire
  • thickness of the wire
  • temperature

  = more resistance