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5.8 Circuits:

A circuit is made up of a power
supply, connecting wires &
various components that allow
current to leave a power source,
travel through the components &
return back to the power source.
Common Electric Symbols


Battery/Power
Source
Bulb
Common symbols (cont’d)

Switch

Push-button
Switch
Resistor

Voltmeter

Ammeter

V
A
What are we doing?





Send 1 person to pick up:
 1 battery &
 1 light bulb & holder
 2 wires
Make the light bulb light up!
Once you do … go get a switch and
add it to your circuit.
Draw a circuit diagram. HAND IT IN.
Return the materials.
Circuits
Power Supply
A
Switch
Light bulb
Ammeter
Resistor
Voltmeter
v
Trick to help identify type of circuit:
Series:Pen follows wire
Types
of
Circuits:
Parallel: Pen can go in more than one direction

There are 2 types of circuits:
1.
 2.

SERIES
Series Circuit
Parallel Circuit
PARALLEL
Series Circuits:




Components are connected end to end
Current only follows one path
If one part of the circuit is broken, the
entire circuit will stop functioning
Eg: Some Christmas tree lights
Parallel Circuits:



Current can follow at least 2 different
paths
If part of the circuit is defective another
part may still be able to operate.
Eg: headlights on a car
Series or Parallel?
1.
2.
PARALLEL
SERIES
3.
4.
A
PARALLEL
SERIES
A
AST stop here!

In a series circuit, the Amps remain
constant throughout the whole circuit
Amps =
2A
Amps =
2A
Amps =
2A
Volts, Ohm’s and Amps in a Series
Circuit

In a series circuit, the Amps remain
constant throughout the whole circuit
Amps =
2A
Amps =
2A
Amps =
2A
However, in a series circuit at each resistor the
=
VTvoltsVchange.
+
V
+
V
+
…
When
you
add
up
all
the
voltage
1
2
3

at each resistor, you end up getting the total
volts going through the circuit.
Volts1 = 2V
Volts total = 7V
Amps = 2A
Volts2 = 3V
Amps = 2A
Volts3 = 2V
Amps = 2A

In a parallel series, each line of wire has
a different amount of amps. When
added the amps together, you get the
total amount of amps in the entire
circuit.
Amps3 =
1A
Amps2 =
.5A
Amps1 =
.5A

However, in a parallel circuit if you have a total
of 3 volts in the circuit, each resistor will only
have 3 volts
Volts3 =
3V
Amps3 =
1A
Volts2 =
3V
Amps2 =
.5A
Amps1 =
.5A
Volts1 =
3V
Volts Total
= 3V
5.9
Kirchhoff’s Laws about Volts, Ohms & Amps.
For circuits in:
 Series:



Amps stay the same everywhere in the
circuit.
Volts are split over each resistor but add
up to Vtotal.
Parallel:


Amps split at each resistor but add up to
Atotal.
Volts stay the same everywhere in the
circuit.