Presentation on theme: "T OPIC 2 – E LECTRICITY WITHIN A CIRCUIT Science 9 - Electricity."— Presentation transcript:
T OPIC 2 – E LECTRICITY WITHIN A CIRCUIT Science 9 - Electricity
H AVE YOU EVER LOOKED INSIDE OF A COMPUTER ? Electronic devices often contain hundreds of parts, connected in carefully designed circuits!!!
W HAT IS A CIRCUIT ? Circuit : provide a continuous pathway for charges to move
C IRCUIT E LEMENTS & D IAGRAMS All circuits require 4 basic elements: 1. Source : source of electric energy Ex: battery 2. Conductor : the wire through which current flows 3. Load : items along the circuit that convert electricity into other forms of energy Ex: light bulbs, motors, heaters, speakers 4. Control : a switch or device that can turn the circuit or devices along it on or off
D RAW THE SYMBOLS FOR THE FOLLOWING ( PG. 273): Conducting wire Cell Battery Lamp Switch Resistor Why would we use symbols to show a circuit instead of using words?
Y OUR CIRCUIT DIAGRAM SHOULD MEET THE FOLLOWING CRITERIA : Drawn with a pencil on unlined paper or graphed paper Place components in rectangular or square arrangements Make conductors straight lines with right angles Do not have conductors cross Draw neatly, making symbols consistent size
D RAW THESE C IRCUITS : 1. Wire, two light bulbs, a switch and a battery 2. Wire, 1 light bulb, one resistor, and a cell. 3. Wire, 2 batteries, 1 light bulb, and a motor. 4. You can measure current by using an ammeter. It’s symbol is a capital “A” with a circle around it. Draw a circuit with an ammeter, 3 light bulbs, a switch, and wire. Will this circuit work? Why or why not?
M EASURING CURRENT Current : number of electrons that pass by a spot in a certain time Symbol: I Measured in: amperes (A) Device to measure: Galvanometer: weak current Ammeter: stronger current galvanometer
M EASURING VOLTAGE Potential Difference : difference in energy per unit of charge between one point in the circuit and another – commonly referred to as voltage Symbol: V Measured in: volts (V) Device to measure: Voltmeter All forms of energy are measured in joules (J)
T O DO : Read: “Rivers of Electricity”- page 278 Circuits Lab!