Electricity What is electricity Electric current flow of

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 120 V 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