Lesson 04
1) Check HW
On the computer, check your Electrostatic Series Homework sheet by looking at the answers on the class web site.
2) Exit Card
Electrostatic Series Leprechaun Question
3) Finish Yesterday's Note
Find "Lesson 03 ­ Contact and Induced Charge Separation" on the class webpage and finish copying the rest of the note. 4) John Travoltage PhET
­ Download the "John Travoltage PhET Worksheet" from the class website and save it to your Science Folder. Follow the instructions and type out your answers on the worksheet while doing the activity. ­Save your answers in your Science folder then login to D2L elearning and upload your answers the 'John Travoltage PhET' dropbox. 5) Note on Electric Discharge
­ We will fill this in together.
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Did You Know?
People in ancient times imagined that lightening was created by an angry god.
Thor was the mythological god of thunder and was thought of as the strongest of all the Norse gods. One of the days of the week is named after him­ Thursday (Thor's Day). Today we know lightening is a giant example of an electric discharge.
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Conditions for Electric Discharge
Review of Charging by Friction
When two neutral objects rub against each other and have a different levels of attraction for their electrons, electrons will move from one object to another. Each electrostatic
insulator
object must be an ________________________. The _____________________ series helps predict which object will gain ____________________ and become electrons
_______________ and which object lose _______________ and become negative
_________________________.
positive
protons
Static discharge is when electrons travel through the air from one object to another. When the electrons travel rapidly through the air, the air is heated and light is generated. This is seen as a small arc.
John Tavoltage Phet
What conditions caused the static discharge to occur?
There are 3 Keys factors that influence static discharge: 1) The medium 2) The size of the charge difference 3) The distance between charged objects
1) Medium
Definition ­ the substance the electrons are travelling through. Examples __________________________________________
Conductors vs. Insulators
The structure of a material affects its ability to transfer electrons. easily
A conductor allows electrons to move within the material rather ________________ resists
whereas an insulator ____________________ internal movement of electrons. Water is a better conductor than air!
Humidity is a measure of the amount of ________________ in the air. Water is a water
better ______________ than dry air. Static buildup happens less in humid weather as conductor
the electrons that build up can dissipate to the air. 5
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2) Size of the Charge Difference
charge difference
The greater the ________________________, the greater the potential for discharge. The more John rubbed his foot on the carpet, the more the chance that he was _shocked_. Damage, however, will only happen when the discharge occurs.
Circle which scenario has a greater charge difference.
Scenario 2
251 protons, 248 electrons
Scenario 1
20 protons, 15 electrons
3) Distance Between Charged Objects
The smaller the distance between the charged objects, the The
the greater the chance the electrons jump to the door knob.
Videos on Lightning
National Geo Lightening Strikes (6 min)
CN Tower (2 min)
Birth of a Bolt (2 min)
https://www.youtube.com/watch?v=7qgM1A3pgkQ
https://www.youtube.com/watch?v=L1HhRAUqFqM
Lightning Lightening is the arcing of a large charge build up. Consider the conditions for static discharge when answering the following
1) Why does lightning hit tall objects?
2) Why does lightning often happen during storms?
3) Why is lightning so bright and dangerous?
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