Electricity & Magnetism

ENERGY RESOURCES AND POWER PLANTS

Electric currents and magnetic fields

• An electric current produces a magnetic field

Electric Circuits

• An electric circuit has a source of electrical energy. Circuits have devices run by electrical energy. Circuits are connected by conducting wires.

Parallel circuits

• In a parallel circuit there are several paths for the current to take.

Electromagnets

• An electromagnet is a strong magnet that can be turned on and off.

Static Electricity

• Opposite charges attract

• Like charges repel

Lightning-Static Discharge

• Lightning is an example of static discharge. During thunderstorms, air swirls violently. Water droplets within the clouds become electrically charged. Electrons collect in the lower parts of the cloud. Electrons move from areas of negative charge to areas of positive charge. As the electrons jump, they produce a spark. The spark is lightning.

Fuses

• A fuse is a device that contains a thin metal strip that will melt if there is too much current flowing through it.

Circuit Breakers

• A circuit breaker is a safety device that uses and electromagnet to shut off the circuit when the current gets too high. Just Pull back the switch to reset the breaker.

Electric Motors

• When a current carrying coil of wire is placed in a magnetic field, electrical energy is converted into mechanical energy. An electric motor is a device that uses an electric current to turn an axle.

Generator

• An electric generator converts mechanical energy into electrical energy. (Energy is never created, nor destroyed, but converted from one form to another).

Turbines

• A turbine is a circular device made up of many blades. The turbine is like a propeller. The turbine turns the generator that converts mechanical energy to electrical energy.

Electric power can be produced in several ways. Each kind of generating power converts a

particular kind of energy into electrical energy.

Energy is stored in the nucleus of the atom. When the nucleus is split, the energy that is released is used to heat water. The water turns into steam,

which expands and turns a turbine.

Solar Energy-The sun’s rays can be focused on a tower by large mirrors to boil water. The resulting

steam then turns the turbine.

Geothermal Energy- In a few locations on Earth, the underground water near the molten rock is heated until it becomes steam. This steam, which can be obtained through steam vents or drilling, is

then used to turn the turbine.

Energy from falling water- Hydroelectric plant near the bases of dams or waterfalls use water to turn

the turbines.

Tidal Energy-As the tide moves in and out in a basin behind a dam, the moving water can be

used to turn the turbine.

Energy from fossil fuels-Coal, oil, and natural gas can be burned in generating plants to produce steam. The steam pushes against

the blades of the turbine, causing it to turn.

Energy from wind- A windmill is essentially a turbine. As the wind blows, it turns the blades of

the windmill, which then turn the generator.

The Energy generated goes from the generating power plant…

To the step up transformers (increase voltage)…

To the high voltage transmission lines….

To the step down transformers at the sub-stations…

To the step down transformers (decrease voltage) on poles, or on the ground …

To homes…

Paying for Electricity

• The total amount of energy used by an appliance is the power consumption multiplied by the time the appliance is used.

Thomas Edison opened his first generating power plant in 1882.