Download Electric Circuits

Electric Circuits
Series and Parallel Circuits
Circuit Diagrams
• An electric circuit is a complete path through
which charge can flow
• Circuit diagrams use symbols to represent
parts of a circuit
• Circuit diagrams show a source of electrical
energy, and devices run by electrical energy
Circuit Diagrams
• A circuit diagram will show one or more paths
for the charge to flow
• Switches are where the circuit can be open
• An open circuit occurs if a switch is open then
the circuit is not a complete loop and the
current stops
• A closed circuit is when the switch is closed
and the circuit is complete
Series Circuit
• A series circuit has only one path that the
charge can flow
• If one element in a series circuit stops working
then the whole circuit will not work
• Each bulb in a series circuit adds resistance
and makes all of the bulbs dimmer
Parallel Circuit
• A parallel circuit is when two or more paths
through which the charge can flow
• If one element stops working then the charge
can flow along another path
• This is common in houses
Power and Energy
• The rate at which electrical energy is
converted to another form of energy is electric
power
• The unit is joule per second or watt (W)
• Power is often in kilowatts (kW)
• Power = current x voltage or P = I x V
• P(watts) = I (amps) x V (volts)
Example
• An electric oven is connected to a 240 volt line
and it uses 34 amps of current. What is the
power used by the oven?
• Current = I = 34 amps
Voltage = V = 240 volts
Power = I x V
• Power = 34 amps x 240 volts
Power = 8160 watts
Electrical Safety
• There are several things needed to make a
house safe such as correct wiring, fuses,
circuit breakers, insulation, and grounded
plugs
• In the US most houses have an average of 120
volts and each device increases the current
• If too many devices are used it may cause a
fire
Home Safety
• A fuse prevents current overload in
a circuit
• A wire in the fuse will melt if there
is too much current
• This is how we “blow a fuse”
• Most houses now use circuit
breakers
• A circuit breaker is a switch that will
open when a current is too high