Post on 03-Jan-2016
Static Electricity• Static electricity is when a charge
is built up on an object. The charges do not move. This is usually caused by friction. Examples: feet rubbing against the carpet, combing hair, rubbing a plastic strip with a cloth.
Static Electricity• Static electricity
cannot hurt.• Static electricity
does not supply any useful energy.
There are 3 types of charges.• Positive• Negative• Neutral – This
means that there is no net charge on the object. There are equal numbers of + and – charges.
• Opposite charges will attract.
• Like charges will repel.
• Neutrally charged objects are attracted by both + & -.
• This is a very strong force.
Conductors and Insulators• A conductor is a
substance that allows current to flow through it.
• Examples: copper & most other metals, graphite, the human body
• An insulator is a substance that does not allow current to pass through it easily.
• Examples: plastic, rubber, glass, wood.
Current Electricity• Current is when the charges are
moving. The movement allows them to do work for us. Examples: lightning, a “shock” from a door knob, current in a wire
Current• Current can cause
pain and/or be fatal. Care is required.
• Current also supplies a great deal of useful energy.
Voltage• The amount of energy carried by the
electrons moving through the circuit.• Measured in volts (v)• 1 volt = 1 joule per coulomb of
charge• The voltage is set by the energy
source. Example: a 1.5 volt battery or a 110 volt wall socket
Current• The flow of electrons through a
conductor.• Measured in amperes (amps)• 1 amp = 1 coulomb per second• Set by the appliance.
Resistance• The tendency of a
material to resist the flow of charges.
• Measured in ohms ()• The filament in a light
bulb has a high resistance. This is why it gets so hot it glows.
Series Circuits• In a series circuit
all the current must flow through every appliance in the circuit. If one of the appliances goes out, they all go out. Notice that the energy seems to run out.
Parallel Circuit• In a parallel
circuit the current flow splits up and goes to different parts of the circuit. If one bulb or appliance goes out, the rest stay on. All bulbs are equally bright.
Direct Current• Direct current is
when the electrical current moves in one direction all the time.
• Examples: batteries
Alternating Current• Alternating current
is when the direction of the flow of current changes 60 times per second. It can be carried long distances from power plants
• Example: wall sockets
Power• The amount of energy used in a period
of time; P = energy / time• For electricity: Power = voltage x
current (P = v x i)
• Units: watts or kilowatts (1000 watts)