Comp TIA A Certification 220602 Mercy Vocational High School

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Comp TIA A Certification 220-602Mercy
Vocational High School

• Instructor Mr. Maphorisa
• 2007/2008

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Electricity and Power Systems

• Electricity is the source of energy for
  electronic equipment, including personal
  computers.
• Characteristics of Electricity
• -Electricity is the flow of electrons which are
  the fundamental build blocks of matter.
• -A conductor is a material that permits the flow
  of electricity e.g. most metals. An Insulator is
  a material that does not permit the flow of
  electricity e.g. mot ceramics, plastics and
  gases.

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Voltage

• Voltage is the force of electricity caused by a
  difference in charge, or electrical potential at
  two locations. This value is measured in volts,
  is also called potential difference or potential.
  
• Current is a measure of the flow of electrons
  past a given point. Current is measured in AMPs
  or AMPERES. An amp is a count of electrons per
  second.
• Current flows only on a complete circuit (closed
  circuit)
• When a circuit is not complete is called open
  circuit.
• A switch interrupts the current flow thus open
  circuit.

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AC and DC current

• When current flows in a single direction at a
  constant voltage through a circuit is called
  DIRECT CURRENT (DC). E.g. batteries provide this
  sort of current.
• Current that flows repeatedly back and forth
  through the circuit at constantly varying voltage
  level is called ALTERNATING CURRENT (AC) .
  Example building electrical service, most house
  hold equipment require AC to operate.

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Resistance and Impedance

• Resistance is a force that opposes the flow of DC
  current through a conductor. Impedance is like
  resistance but applies to AC only.
• Resistance and Impedance are measured in ohms.

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Electrical Power and Energy

• Electrical power is measured in watts.
• PVI