What IS Electricity?
Matter that has an
electric charge causes electricity. All matter is made of atoms, and atoms are made of
protons, neutrons, and electrons. The protons and neutrons are in the nucleus. Protons
have a positive electric charge. Neutrons have no charge. So the nucleus has a positive
charge. Electrons move around the nucleus. They have a negative charge. Things with
opposite electric charges attract each other. So the electrons are attracted to the
nucleus.
As long as an atom has
the same number of protons and electrons, the atom has no charge. But an atom can lose
electrons. When you comb your hair, electrons from your hair may come off onto the comb.
Because your hair has lost electrons, it has a positive electric charge. Because the comb
gained electrons, it has a negative electric charge. The movement of charged particles in
many directions is called static electricity. Electrically charge matter whose particles
all move in the same direction makes current electricity.
How is Electricity Made?
Dry cells are one
source of electrons for current electricity. Dry cells are not really dry. The outside of
a dry cell is made of one kind of metal. In the middle is a post made of a different
metal. Inside the cell is a paste of chemicals. The chemicals react with the metals. One
metal loses some electrons, and the other metal gains the electrons. As the chemicals
react, a flow of electrons forms an electric current. So chemical energy becomes electric
energy.
How Does Electricity Travel?
A conductor is a kind
of matter that electrons can move through easily. Metal wire is the conductor we use most
to carry electricity. Matter that electrons cannot move through easily is called an
insulator. Rubber is a good insulator. Electric wires are often covered with rubber to
keep the electrons moving along in the wire.
The path taken by an
electric current is called an electric circuit. Electric current flows from the source of
the electricity through a wire. At the end of the wire is something that uses electricity,
such as a light bulb. Most electric circuits have a switch. When the switch is off, the
circuit is open. The current’s path is broken. When the switch is on, there are no
breaks in the path. It is a closed circuit. The current can complete its path.
How do Fuses and Circuit Breakers Work?
You may have seen that
when electricity flows through a circuit, some electricity changes into heat. Sometimes
too much current goes through a circuit. The wires of the circuit can get very hot. The
heat could start a fire. To keep fires from starting, fuses can be put in a circuit. A
fuse is like a little light bulb. It has a wire inside that melts easily. When the circuit
has too much current, the wire heats up. The wire becomes so hot that it melts. The
circuit is broken, and no more electrons can flow through it.
Circuit breakers are
often used instead of fuses. A circuit breaker has a switch that works like a fuse. If the
electric current is too great, a switch opens and stops the current. When a circuit
breaker breaks a circuit, it does not have to be replaced. The switch can be closed, and
the circuit will work again.
How Can We Use Electricity Safely?
Machines run by
electricity make life easier. But any machine or tool run by electricity must be used
safely. Electricity can be dangerous.
People should take care when using electric outlets. Outlets are meant for plugging in
electric cords only. Never put anything else into an electric outlet. An object put into
an outlet may carry electricity. Electricity can burn the hand of the person holding the
object. When cleaning or fixing an appliance, be sure to pull the plug out of the outlet.
Water is a good
conductor of electricity. Keep electric appliances away from water. For example, never
wash or bathe with a hair dryer near you. If it fell into the water, the electric shock
could kill you instantly.
