Transcript Document

Current Electricity
Current
• A measure of the flow
of charge.
• Ampere: Electrical
measurement of the
flow of electrons.
• 1 Ampere = 1
Coulomb/second.
• 1 Coulomb =
6,250,000,000,000,000,000 Electrons
Current
• Water Analogy: current is
gallons per minute.
• Symbol for Current = I
Conventional Current
• Conventional current
= positive charge flow.
• Electron Flow is in
opposite direction
Current
Current
Voltage
• The force that pushes
electrons through a
wire.
• Electrical Pressure or
“Potential Difference”.
• Measured in Volts
• 1 volt = 1
joule/Coulomb
Voltage
• Water analogy:
Voltage is the water
pressure supplied by
the pump (battery) or a
water tower.
• The symbol for
voltage = V
Resistance
• A resistor hinders the
flow of current
through a circuit.
• Ohm = unit of
resistance (Ω)
Resistance
• Water analogy: a
waterwheel, constriction
in pipe, or other object
that hinders flow.
• Symbol is R
Ohm’s Law
• Relates Current, Voltage, and Resistance.
• I = V/R
Or.. R = V/I
Where Does Voltage Originate?
• V = ∆PE / q
• ∆PE = work done on
charge.
(joules/coloumb)
Relating Voltage to Electric Field
• V = ∆PE / q
– Joules/coulomb
• E = V/d
– Unit is N/C
• Electric field
– directly proportional to
applied voltage
– Inversely proportional to
distance between plates.