Science Notes Electricity:
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Electrons in current electricity move in a steady flow through a conductor
A continuous path for electron flow is called an electric circuit
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Components of a simple electrical circuit
o Load
▪ Device that transports electrical energy into other usable forms of
energy, such as a bulb or a heater
o Energy Source
▪ An energy source
o Conducting Wires
▪ Join all parts of a electrical circuit
▪ Pathway for electrons to flow
▪ Normally made of aluminum or insulated copper
o Switch
▪ Controls current flow in a circuit
▪ Closed = On
▪ Open = Off
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Electrical Cells
o Electrical Cell: Portable device that converts chemical energy into
electrical energy
o Electrical cells are made of two electrodes in a conducting solution called
an electrolyte
▪ Electrodes are the conductors with different charges
o Primary Cells: Cannot be recharged because chemical reactions used to
produce energy aren’t reversible
o Secondary Cells: Can be recharge and reused due to the chemical
reactions being able to be reversed
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There are Two different forms of electrical currents:
o Direct Current (DC)
▪ Electrons flow in one direction, battery provides electrons to loads
o Alternating Current (AC)
▪ Electrons move back and forth, alternating their direction
▪ AC produced through generators
▪ Able to travel longer distance than DC
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There are many ways to produce energy
o Electrical generating stations convert mechanical energy into electrical
energy.
▪ An external energy source is used to push the blades of a turbine
which moves a generator
▪ Generator has a coil of wire inside between two poles of a magnet
▪ When turbine spins, so does coil of wire and electrons are
transmitted into the wire
o Constant flow of electrons through a generator was discovered by
Michael Faraday
o Electrical energy production can be controlled
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Electrical Power:
o Electrical Power: The rate at which electrical energy is produced or
consumed in a given time
▪ Unit for electrical power is the Watt (W)
▪ W = J/S
o Electrical Generating Stations measures in Watt-hours (W-h) and kilowatthours (kW-h) and gigawatt-hours (GW-h)
▪ kW-h = W-h x 1000
▪ GW-h =kW-h x 1000000
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Electric Current: Rate of electron flow past a specific point in a circuit
Potential Difference or Voltage: Difference in potential energy per unit of
charge
Electrical Resistance: The opposition to the movement of electrons as they flow
through a circuit
o Factors that affect resistance
▪ Material
• Conductivity leads to lower resistance
▪ Cross-sectional area
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Thicker wires have less resistance as there are more places
to move
Length
• Resistance increases the longer the wire
Temperature
• Warmer wire means higher resistance