Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Electricity What is electricity? • Electric current – flow of electrons through a _______ • Current (I) is measured by how many __________pass a given point during each second • Ampere – amount of current that flows past a given point in _________ What are parts of an electric circuit? • A source of ________ • Load or _________ • Wires • Switch Sources of electrons • Electrochemical cell _____________ causes a flow of electrons Two types _____cell – batteries in your Ipod _____cell – car battery • Generator – the current running through wires in your house _________ _______________ ____________ Load or resistance • Load – device that uses the electrical energy Light bulb, heating coils in a toaster, microwave oven • The load provides _________ to the flow of electrons • Electrical energy converted into _____, _______, or _________ energy Wires • Wires provide a _______ for electrons to flow • Based on being good conductors Conductors – materials that electrons can move through ________ ex. – copper, gold, silver • Other materials are insulators electrons ________move through easily ex. – wood, cotton, rubber, glass Why are wires covered with insulating material? • Two reasons So electricity running through wires can’t be _______________ So wires can’t touch each other and ______________ – causing a fire What is relationship between current, voltage, and resistance? voltage = current x resistance current : units are _______ voltage : units are _______ resistance: units are ______ V I R Try a problem • What is voltage if current is 1.5 amperes and resistance is 30 ohms? Second problem • What is current flowing through a wire if the resistance is 20 ohms and the voltage is 40 volts? Third practice problem • What is a wire’s resistance if a current of 0.5 amperes flows through a wire and the voltage is 50 volts? What is direct current? • Electrons flow from _____ terminal to ________ terminal • Examples: AAA batteries Car battery Battery charger What is alternating current? • Electricity changes direction ________ • Changes direction at speed of about ____times per second • Electric energy is transferred. Electrons __________ • Advantage Can travel over ______ distances at high _______ How is electrical power charged to your house? • First calculate electric power in watts voltage x current = power • Then multiply watts by hours, and divide by 1000 to get kilowatts • Unit for electric energy is usually _______ One kilowatt of power being used for 1 hour Practice problem • A clothes dryer power usage is 4000 watts • How much energy in kilowatt hours is used if a dryer is used for 30 minutes? Electrical safety • Voltage __________ is what can hurt you. • If your hands and feet are dry and you touch a source of electric house current, then there is 120V difference between the source and the ground you are standing on • Lot of ___________since dry – not much _________flows • What if feet are wet? Resistance _____ and a lot of current can flow