Sci 9 Lesson 5 May 11 - Electric Current Presentation Transcript
Homework from last class:
Answer the following questions:
“ What is an electric circuit?”
“ What is an electric load?”
“ Explain how an electric circuit is like a
person going down a waterslide.”
Read over class notes and check class blog
Chapter 8.2 pp. 280-288 Electric Current
Electric circuit: A complete pathway that allows electrons to flow
Electric load: Any device that transforms electrical energy into other forms of energy
ex: a light bulb, buzzer, heater, and flashlight
pp. 280 - 281
A Simple Circuit: A Battery, Conducting Wires, and a Buzzer p. 280 1) Chemical energy in battery gives electrons on the –ve terminal electric potential energy 2) Electrons are attracted to the +ve terminal and are pushed through the conducting wire to the buzzer 3) In the buzzer, the electrons’ potential energy is transformed into sound energy 4) Electrons travel back to the battery through the complete circuit
Circuit Components and Diagrams
Circuits are made of only 4 basic components:
p. 282 Source: the source of electrical energy Conductor: the wire through which electric current flows Load: a device that transforms electrical energy into other forms of energy Switch: a device that can turn the circuit on or off by closing or opening the circuit source conductor load switch
Circuit Components and Diagrams
Circuit diagram: a drawing using symbols to represent the different components of a circuit
Simple to read diagrams should meet the following criteria:
Draw your diagrams using straight lines .
Make all connecting wires and leads straight lines with 90° (right angle) corners
If possible, do not let conductors cross over one another
Your finished drawing should be rectangular or square
Circuit Drawing Time!
Complete activity 8-2B Drawing Circuit Diagrams on p. 283 .
Identify which circuits are closed and which ones are open .
A closed circuit has no breaks in the path of electrons.
An open circuit does not allow a flow of electrons because there is a break in the path.
As soon as a battery is connected to a circuit, the circuit is closed .
Electrons do NOT need to touch in order to push other electrons
Electrons apply an action-at-a-distance force .
p. 283 Current electricity: the continuous flow of charge in a complete circuit Current electricity is NOT the same as static electricity (charge that remains stationary on an insulator)
Electric current: the amount of charge passing a point in a conductor every second.
Ampere (A): unit for measuring electric current; very small currents are measured in milliamperes (mA)
1 A = 1000 mA
Ammeter: a device used to measure the current in a circuit
p. 284 Ammeter symbol on a circuit diagram
The flow of electricity is from negative to positive (the flow of electrons).
In the early days of electricity research, scientists mistakenly believed electricity flowed from positive to negative .
Descriptions of this flow from positive to negative still exists today, and is known as conventional current .
p. 284 Conventional current Flow of electricity
Homework for next class:
Complete “Drawing Circuit Diagrams” and “Circuit Symbols” worksheet (both sides)