Presentation on theme: "E(15-2) What is electricity and how it is produced? Static electricity Current electricity."— Presentation transcript:
E(15-2) What is electricity and how it is produced? Static electricity Current electricity
Static Electricity- Definition The electric charge that builds up on an object that has gained or lost electrons is Static Electricity.
Static Electricity- Lightening Lightening: 1.Updraft in a thunderstorm carry rain along. 2.Friction rubs electrons off the drops giving the top of the cloud an all-over positive charge. 3.The bottom of the thunder storm has extra electrons giving it a negative charge. 4.Positive and negative parts attract. 5.When attraction is enough, the clouds give off its energy in a flash of light.
Static Electricity- machines Static charges are temporary and somewhat unpredictable. Photocopiers and air cleaners are two devices that use static electricity. It doesn’t have many other uses as it is hard to control.
Current Electricity Is the flow of electric charge through a wire. It’s quite controllable and has many practical uses. Charges move easily through conductors. Ex. metals especially copper. Insulators are materials that are poor conductors of thermal energy and electricity. Ex. uncharged air, rubber and plastic that are used to wrap electric wires.
Current Electricity How does the light bulb glow?
Current Electricity Where do the charges in the wall socket come from?
Current Electricity How cars work? 1.Turning the ignition key allows electricity to flow from the battery to the starter relay. 2.The relay lets large amounts of current flow from battery through the starter motor and back. 3.The starter motor is a powerful electric motor with gears that make the engine run. 4.The cars pistons draw in a mixture of gasoline and air. 5.A spark from the car’s ignition system makes the mixture explode. 6.As the fuel burns, the pistons turn the engine fast enough, the starter motor shuts off.
Current Electricity Car batteries Why car batteries don’t lose their charge? Because they are recharged every time the car is driven. How? Inside a battery two plates made of different metals hang in a liquid that conducts electricity. Chemical reactions between theses plates and the liquid produce excess electrons. The battery give up some of those electrons when the car starts or when the radio plays. But while the car is moving, a device called alternator sends current back to the battery. The current restores he original state of the two plates, so they are ready to react again and provide electrons when needed.
Current Electricity How electricity is produced? An electric generating station can use any of several resources. 1.At a hydroelectric plant, the energy comes from falling water. In some, a dam holds water as potential energy. In others, the plant relies on the natural flow of a river. In both cases, he water moves over the blades of a turbine, making the turbine spin. A shaft connects the turbine to a generator. Inside the generator a giant magnet surrounds a spinning coil of electric wire. The spinning of a wire in the magnetic field produces an electric current in the wire.
Current Electricity How electricity is produced? 2.Fossil fuel stations burn coal, oil and natural gas. Coal, oil and natural gas are burnt in a large furnace. The heat from the furnace causes water to boil and turn to steam. The pressure of the hot steam turns the turbine that is connected to the generator.
Current Electricity How electricity is produced? 3.In a nuclear plant, the process is the same but the heat comes from splitting atoms. Some people think it’s too risky, others think it’s cheap and beneficial.
Current Electricity How electricity is produced? 4.Solar power, photovoltaic cells made of silicon generate electricity directly from sunlight. No generators are required.
Current Electricity How electricity is produced? 5.Wind farms, where wind turbines turn shafts in generators to produce electricity.
Current Electricity How electricity is produced? 6.Ocean tides are used in coastal communities to generate electricity. 7.Geothermal energy plants turn shafts in generators by using steam that comes from supplies of hot water lying deep under the ground.