ELECTRICITY SPS10. Students will investigate the properties of electricity and magnetism. a. Investigate static electricity in terms of Friction Induction Conduction b. Explain the flow of electrons in terms of Alternating & direct current The relationship among voltage, resistance and current Simple series & parallel circuits
Overview ELECTRICITY Static Electricity Circuits Currents Voltage Resistance Induction Series Direct Conduction Parallel Alternating Friction
Essential Questions What does it mean when something is electrically charged? How can objects become electrically charged? Why can small birds sit on high-voltage power lines? What characteristics of material make it a good conductor or insulator? Why are insulators attracted to charged objects? Why are alternating currents commonly used in household applications?
We Take It For Granted! Look around the room How many objects, devices or appliances require electricity? Think about your homes.how many things require electricity? What happens when there s a power outage? Our lives are put on hold! Why? We are extremely dependent on ELECTRICITY!
Electricity Origins? Where does it come from? Power plants Who makes it? Nobody! It is not made it s converted! How is it converted? The force of steam is converted into mechanical energy which causes a turbine (a huge wheel thingy) to rotate. The turbine is connected to an electrical generator that produces current (electricity). How does it get to your home/school? It travels along wires to your home/school.
Static Electricity What happens when you drag your feet on carpet and then touch a doorknob? You get a SHOCK! Why? Walking across the carpet causes electrons to leave the carpet and enter your body. When you touch the metal handle, the extra electrons jumped from your hand to the metal. When the electrons move from one place to another, energy is transferred.
Transfer of Electric Charge Static electricity charges can build up in three ways:
Transfer of Electric Charge Charging by is the acquiring of charges when an object that has an opposite charge is. Charging by is the acquiring of charges by. If a charged object touches a neutral object, are. Charging by is the acquiring of charges by having objects across each other.
Electric Current The of from one place to another is called. Electric current is measured in. An ampere tell us how much current is moving past a point in a circuit in one second. One ampere is equal to electrons per second. Ampere may be shortened and called the.
Circuits When electrons travel in a current, the path they follow is called a. The circuit begins at the power source to the and back to the power source. If the circuit is unbroken, it is If the circuit broken, it is. CLOSED OPEN
How To Draw A Circuit Cell (power source) Wiring Closed switch Open switch Bulb
Conductors & Insulators Let s remember. Conductors conduct electricity: Insulators don t: Not all conductors allow electricity to pass through them in the same way. Not all insulators slow down electricity in the same way
Resistance A measure of how hard or how easy it is for electric current to flow through a material. Measured in. Causes electrical energy to change into and energy. Depends on three things
Resistance Example: Think of 2 water hoses. One has a larger opening in the middle. If a pump is pumping water at the same rate through both hoses, which one will produce more water in one minute? The hose with the larger opening. Conductors have low. Insulators have high.
Resistance Can be calculated voltage/current Voltage is the energy that a power source gives to the electrons in a circuit
More on Circuits Circuits can be in a or. Series circuits have a power supply (battery) and wire, but they contain multiple electrical devices. Example: decorative lights What happens on some strings when one bulb blows? If the entire string of lights stops working, you have a series circuit.
Parallel Circuits Parallel circuits have more than one path for the current to follow. Homes are mostly wired this way. If you have a string of decorative lights, if one blows, the others will remain lit.
Fuses Provide safety for circuits to prevent fires Fuses have metal on top that melts if it gets too hot. When it melts, the circuit is broken. What happens when a circuit is broken? It stops transporting electricity.
Circuit Breakers Are also safety devices to prevent fires When they get too hot, they switch themselves off or open the circuit. What happens when a circuit is open? It stops working! Circuit breakers can be reset
Currents AC: (the current can flow more than one way) DC: (current can only flow one way) AC is what we have in our homes. DC is what batteries offer.
Let s Review Electricity is the flow of electrons Static electricity is a buildup of electric charge The charges can build up by induction, friction or conduction Current, the rate of flow of electricity, is measured in amperes. A closed circuit is complete & unbroken An open circuit is incomplete & broken
Review Drawings of circuits are called schematics Resistance measures how easily electricity flows through a material