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___
 Electrostatic
Lab Simulations Part I
Directions: Open your web
browser to:
http://www.hinsdale86.org/staff/jliaw/. Go to Explorations / Electricity &
Magnetism / Electrostatics / Electrostatic Lab Sims Part I. You will need to
have Shockwave & Java installed for some of the sims—if it’s not installed on
your machine it will automatically install itself or follow the link.
Introduction to Electrostatics:
Open up the following PowerPoint and use it to answer the following questions—
USE THE RIGHT AND LEFT ARROW KEYS TO STEP THROUGH THE SLIDESHOW:
1. What are the two basic types of charge?
2. Who is the guy that named the types of charge, did he do it right?
3. What type of charge does an object possess if it has an equal number of
positive and negative charges?
4. What units is charge measured in?
5. What’s the difference (on
the atomic scale) between conductors and insulators?
6. Define Tribocharging.
Look at the Triboelectric Sereies, if rabbit fur is giving away electrons, which
material wants to take them more readily, vinyl or silk?
7. Where does charge reside
in a conductor? If the conductor is a weird shape then where does most of the
charge collect at?
7b.
Using the charge determine the charge (plus or minus) of the materials rubbed
against another:
a. rabbit fur_______ vs. rubber balloon________ (you
should know this one already)
b. cotton shirt_______ vs. human skin___________
c. glass window_______ vs. silk curtain____________
John Travoltage:
8. What happens as you rub John’s foot against the wool
carpet? Why (hint: explain this in terms of the triboelectric effect!)
9. Move John’s hand far away from the door knob and then build up some
charge by rubbing his foot. Where does this charge settle in John’s body? Why
(hint: look back at section 1!)
10. Go ahead and give John a shock by moving his
hand close to the door knob when he has some charge built up in his body.
Explain what happens when we get a static shock.
Balloon
Phun:
11.
Rub the balloon on the sweater. Why does the balloon want to keep close to the
sweater?
12. Move the balloon near the wall. Draw a picture of the charges in the
balloon & wall. What is the wall’s charge?
12b. So when an object like the wall becomes polarized which charges move and
why?
The Electroscope:
13.
What is an electroscope and what is it used for? How does it work?
14.
How do you charge an electroscope by contact (conduction)?
15.
How do you charge an electroscope without contact by induction? Draw a picture
and list the steps.
The Mighty Electroscope:
16. How do you charge an
electroscope by contact (conduction)? – list the steps, draw a picture:
16b. How do you charge an
electroscope by induction? –
list the steps, draw a picture showing the charges
16c. Compare and Contrast charging by induction and conduction.
a. which one requires grounding?
b. which one ends up with the same charge as the charged source
(stick)?
c. which requires touching the electroscope by the charged source
(stick)?
d. which one requires you to separate the charges with the charged
source (stick)?
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Charging A Pith Ball With A Rubber Or Glass Rod:
17. What happens as you bring
the rod close to the pith ball without actually touching it? What happens after
the rod makes contact with the ball? Is this the same effect with both rods?
(hint: make sure you re-ground the pith ball in between trials!)
18. What is the charge on the pith ball after being
touched with a rubber rod? How about after being touched with a glass rod?
19. What method of charging the ball are you using
in this setup, conduction or induction?
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Losing
Charge:
20.
How does a charged object lose its charge to the
atmosphere?
Lightning Phun:
AND More Lightning Phun
21. What causes lightning? Draw charges
in clouds & the ground:
22. Which
charge moves toward earth?________ Which charge move toward the clouds? ______
More Lightning Physics:
23. What
causes the thunder associated with lightning?
24. What happens to the build-up of charges during each lightning strike?
25. Clouds and the ground make-up a capacitor- 2 charged areas with a
dielectric material in between.
What is the dielectric material separating clouds and the ground?
(rhymes with fair!)
Coulombs’ Law:
26. Draw the picture of a negative rod touching two connecting metal spheres
(SHOW THE CHARGES!)
27. Why do electrons flow from the rod into the spheres and not the other
direction? (think about whether the rod or spheres are neutral to begin with)
28. If the spheres were not conductive, but insulating draw a picture of where
the extra electrons would go
Fast forward to section 4: Coulomb’s law
29. Draw a picture of 2 charged
objects q1 and q2 at a distance “r” apart. Write down
coulomb’s equation for force F.
30. Suppose someone calculates a force of -10 Newtons for two charges.
How can you tell if the charges are opposites or like charges? (hint:
think if the force is attractive or repulsive)
31. The equation for the force of attraction for gravity looks similar to
Coulomb’s law: Force= k*m1*m2 / r2.
The only difference is the constant k (smaller for gravity) and the use of
masses (m1,m2) instead of charges.
Why are both laws called an Inverse Square Law? Which force can only
attract other objects?
32. Suppose the force between 2 objects is + 12 Newtons. If their distance
apart was doubled,
what would be the new force and how do you know if it’s attractive or
repulsive?
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