Electric Circuits and terms

1
Electric Circuits and terms

• Electric circuits move charges around to deliver
  energy

2
Electric Circuits

• Charges move when there is a difference in
  electric Potential. Electric Potential (think of
  potential energy) is called electric Voltage
• Voltage is the driving energy for a circuit and
  it causes charges to move around.
• Charges move around and deliver energy
• The movement or flow of charges is called
  electric current (coulombs/sec amps)
• Current is measured in amps, the symbol for
  current is I.

3
Electric Current

• The amount of electric current depends on the
  amount of Voltage applied (think of the amount of
  energy available) and depends on the resistance
  in the circuit
• For circuits we often use the analogy of flowing
  water. Voltage water pressure, current flow
  rate, and resistance is the size of the pipe (or
  friction in the pipe)

4
Electric circuits

• Resistance is measured in Ohms.
• Light bulbs, toasters, hair dryers, etc. and
  basically just resistors which use up energy.
• Ohms law relates how much current flows in a
  circuit.
• Ohms law V I x R, Voltage current x
  resistance.

5
Electric Power

• Lightbulbs are rated in power units watts.
• Power energy per time.
• For electric circuits, P V x I.

6
Summarize circuit terms

• Voltage This is the amount of electical energy
  supplied. Charges carry around energy and
  transfer this to things like lightbulbs.
• Current This is the flow of charges or how many
  charges flow per second. Measured in Coulombs/sec
  Amp (symbol is I)
• Resistance A light bulb acts like a resistor
  which uses up energy
• Ohms law (relates the above 3 terms V I R) or
  Voltage Current x Resistance.

7
Electric Circuits

• V(volts) I(current) x R (resistance)
• P (power) V x I V2 / R I2 x R
• P power watts
• I current amps
• R resistance ohms
• V Volts (energy)