Download File

Series and
Parallel Circuits
Science 9
Series Circuits
• A circuit that has only one path for the electrons
to follow is called a series circuit.
• If the switch is opened, or a light bulb is removed
or burns out, all of the electrons must stop.
Parallel Circuits
• A circuit that has more than one possible path for
electrons to follow is called a parallel circuit.
• The electrons have more than one possible way
to get from the negative terminal of the battery
to the positive terminal.
Voltage , Current and Resistance in
Series Circuits
• In a series circuit, the charge that leaves the battery “loses”
all of its voltage before returning to the battery.
• The sum of the voltage lost on the loads (in this case, light
bulbs), equals the total voltage of the battery.
Voltage , Current and Resistance in
Series Circuits
• BUT…in a series circuit, the current stays the
same all through the entire circuit, no matter
where we measure the current.
Voltage , Current and Resistance in
Series Circuits
• When you place resistors in series, it increases
the total resistance of the circuit – the
resistances just get added together. This
means that the total current moving through
the circuit will be decreased.
Voltage, Current and Resistance in a
Parallel Circuit
• The voltage in a parallel circuit stays the
same, no matter where you measure it.
Voltage, Current and Resistance in a
Parallel Circuit
• The current does not stay the same
throughout a parallel circuit because the
electrons get split up between multiple
pathways.
Voltage, Current and Resistance in a
Parallel Circuit
• The location where a circuit divides into
multiple paths, or where multiple paths join, is
called a junction point.
• The current across different resistors will be
different, but the amount of current entering
a junction point must be equal to the amount
of current exiting the junction.
Voltage, Current and Resistance in a
Parallel Circuit
• Resistors placed in parallel decrease the total
resistance of the circuit.
Find the current through resistor 2.
Find the voltage across resistor 2.
Find the current through resistor 2.
Find the voltage across resistor 2.