An electrical charge is an electrical property
of matter that creates a force between objects. There are
two types of charges, positive and negative. Positive charges
are associated with protons and negative charges are associated
with electrons. If there is an equal balance between protons
and electrons (positive and negative charges) then the object
will have no net charge. When an objects balance of protons
and electrons is offset, the object becomes charged. The
magnitude of the imbalance is directly related to the magnitude
of the overall charge. If an object has more electrons than
protons it will have a overall negative charge.
Opposite charges attract each other and like
charges repel each other. Charged particles do this because
of electrical force. Electrical force is the attraction
or repulsion between two objects due to their charge. The
force between two charged particles is dependent on the
strength of their charges and the distance between the two
charges. Its force is directly proportional to their charges
and is inversely proportional to the square of the distance
between the two objects.
Some materials are good conductors, that is
they can transfer charges easily and some materials are
good insulators, that is they do not transfer charges.
Electric potential energy is the potential
energy of a charged object due to its position in an electrical
field. (i.e. the closer two like charges are together the
greater the electrical potential energy). The difference
in electric potential energy between two positions is called
a potential difference. This is measured in volts (Joule/coulomb).
When charges move from a position of high electric potential
energy to a position of lower electric potential energy,
the rate that electric charges move through the conductor
is called current. When the conductor slows down the speed
of energy transfer (current), we call it a resistor. The
relationship between voltage current and resistance can
be expressed like this: R=V/I where R is the resistance,
V is the voltage and I is the current.
Electrical circuits provide a path for movement
of electrical charges between two positions of differing
electric potential energy. When appliances (resistor) are
placed in series in an electrical circuit, electrons have
a single path to follow. Because of this, all devices (resistors)
that are in the series circuit will receive the same amount
of current. Devices can also be set up in parallel. In this
situation, there are more than one paths for electrons two
follow. Because of this, the sum of the current through
all of the devices equals the total current.