• Electricity is seen around us every day.
• Electrical outlets are found throughout our
• Lightning bolts are seen shooting from the sky
• We use electricity to power the things we use
every day like our TVs and our computers.
The basics of Electricity
• Electrons are what start
• Electrons are found in
atoms and have a
• Every atom contains one
or more electrons.
• Electrons are tightly bound to their atoms in
materials like wood, glass, plastic, air, and
• Since the electrons can’t move, they don’t
conduct electricity very well.
• These materials that don’t conduct electricity
well are called electrical insulators.
• Most metals like
gold, silver, copper, aluminum, iron, etc. have
electrons that can detach from their atoms and
move around freely. These are called free
• The free electrons moving around make it easy
for the electricity to flow through these metals
making them good conductors of electricity.
• These kinds of metals that conduct electricity
well are called electrical conductors.
• An electrical circuit is a device that uses electricity to
perform a task like powering your lamp.
• Electrical circuits always have a source of electricity
(for example a battery), a load (a light bulb), and two
wires that carry the electricity between the battery and
• The electrons go from the source through the load and
then go back to where it started at the source.
• There are also materials called resistors that are
present in circuits that slow down the flow of the current
• There are different types of electrical circuits; there are
parallel circuits and series circuits.
• In a series circuit there is only one path for the
electrons to flow.
• The resistors in a series circuit are connected
together in a line.
• Current flows through each resistor because
there are no other paths to follow.
This is a picture of a series circuit. It has three
resistors in a line and the current passes through
them all. R1, R2, R3, are the three resistors and
the current flows in a clockwise direction.
• In a parallel circuit there is more than one
continuous path for the electrons to flow.
• There are several pathways lined up parallel to
each other that electricity can pass through.
• Each pathway has its own resistor.
• As the current flows though the circuit, the
current is split because current goes through
each of the pathways.
This is a picture of a parallel circuit. The R1, R2, and R3,
represent the three resistors it has and the current flow goes
in a clockwise direction.
Circuits in the real world
• If one of the light bulbs is
taken out or damaged, the
other bulb will not light up.
• Why? Because the electricity
cannot pass through the
• If one light bulb is taken out or
damaged, the other bulbs will
still light up.
• Why? Because the current can
still pass through the other
• In our homes, each room has it's own parallel
lighting circuit so, if a light bulb blows, the other
light bulbs stay lit.
• Cities use parallel circuits to power their
buildings and homes so that each place can get
the same amount of electricity and so if one area
goes out the whole city does not.
Examples of Series Circuits
• Water heaters use a series circuit. Power enters through the
thermostat, which you set at the temperature you want it to be at.
When the water reaches the correct temperature, the thermostat will
cut off the current to the heating element, leaving the current with
no other paths to follow. This will leave the water at the set
• Lamps are a series circuit. When the switch is turned on, current
will flow to the light bulb. The current can only follow one path.
• Freezers and refrigerators are also series circuits. It works similar to
the water heater. If they get hotter than the set temperature on the
thermostat the compressor will turn on dropping the temperature
on the inside. Once it gets to the desired temperature the
compressor will turn off again.