Presentation on theme: "Electricity. What is electricity? Electric current – flow of electrons through a _______ Current (I) is measured by how many __________pass a given point."— Presentation transcript:
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 V I R current : units are _______ voltage : units are _______ resistance: units are ______
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