today 2/24 read 18.6 about e-fields note we put e-field first and force second e-field lines...
TRANSCRIPT
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Today 2/24 Read 18.6 about E-Fields
note we put E-field first and Force second E-Field Lines Chapter 18.7 Today Lab: “Electrostatics”
Read 18.4 in text for background HW: None assigned
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Electrostatics Lab: This should be Fun!
Tools:
•electroscope
•“proof plane”
•metal cup
•ground wire
•charging rod and glass
delicate gold foil
proof plane
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Proof Plane: What happens…(Start with the proof plane uncharged)
...when the metal touches a charged insulator?
proof plane
...when the metal touches an uncharged plate?
...when the metal touches a charged plate?
some rubs off
nothing
charge moves through the conductors
…when the metal touches the center of the plate???
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Two identical positive charges, A and B, are arranged as shown. The distance from point C to A is twice the distance from point C to B. Which of the following best represents the electric field at point C?
e
d
c
b
aA
B C
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e
d
c
b
aA
B C
Two identical positive charges, A and B, are arranged as shown. The distance from point C to A is twice the distance from point C to B. Which of the following best represents the electric field at point C?
![Page 6: Today 2/24 Read 18.6 about E-Fields note we put E-field first and Force second E-Field Lines Chapter 18.7 Today Lab: “Electrostatics” Read 18.4 in](https://reader036.vdocument.in/reader036/viewer/2022082518/56649f1a5503460f94c2febd/html5/thumbnails/6.jpg)
Field Lines
If we want to draw a picture of the E-Field everywhere at once we must fill space with X’s and arrows.
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Pepe le Pew:
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Where is Pepe?
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Where is Pepe?
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Where is Pepe?
The closer we get to the source, the closer together the lines of STINK and the bigger the PU.
PU!
PU!
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What if it’s a HOT DAY?
More STINK means more lines.
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Field Lines
If we want to draw a picture of the E-Field everywhere at once we must fill space with X’s and arrows.
Red “E-Field lines” display the information more clearly.
![Page 13: Today 2/24 Read 18.6 about E-Fields note we put E-field first and Force second E-Field Lines Chapter 18.7 Today Lab: “Electrostatics” Read 18.4 in](https://reader036.vdocument.in/reader036/viewer/2022082518/56649f1a5503460f94c2febd/html5/thumbnails/13.jpg)
Field Lines
If we want to draw a picture of the E-Field everywhere at once we must fill space with X’s and arrows.
Red “E-Field lines” display the information more clearly.
![Page 14: Today 2/24 Read 18.6 about E-Fields note we put E-field first and Force second E-Field Lines Chapter 18.7 Today Lab: “Electrostatics” Read 18.4 in](https://reader036.vdocument.in/reader036/viewer/2022082518/56649f1a5503460f94c2febd/html5/thumbnails/14.jpg)
Electric Field Lines:
direction of E-field vector at any point is parallel to the lines near that point
magnitude of E-field vector at any point is proportional to line density (line spacing)
number of lines leaving or entering a charge is proportional to the size of the charge (more charge, more lines)
away from positive charge and toward negative charge
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What direction would the force point on a small positive charge at 1,2,3?
Compare the size of the force exerted on a small charge at
a. 1 and 2b. 2 and 3
The test charge is doubled when at 2
a. how does the force change?b. how does the electric field change?
![Page 16: Today 2/24 Read 18.6 about E-Fields note we put E-field first and Force second E-Field Lines Chapter 18.7 Today Lab: “Electrostatics” Read 18.4 in](https://reader036.vdocument.in/reader036/viewer/2022082518/56649f1a5503460f94c2febd/html5/thumbnails/16.jpg)
What direction would the force point on a small positive charge at 1,2,3?
Compare the size of the force exerted on a small charge at
a. 1 and 2b. 2 and 3
The test charge is doubled when at 2
a. how does the force change?b. how does the electric field change?
1 larger
![Page 17: Today 2/24 Read 18.6 about E-Fields note we put E-field first and Force second E-Field Lines Chapter 18.7 Today Lab: “Electrostatics” Read 18.4 in](https://reader036.vdocument.in/reader036/viewer/2022082518/56649f1a5503460f94c2febd/html5/thumbnails/17.jpg)
What direction would the force point on a small positive charge at 1,2,3?
Compare the size of the force exerted on a small charge at
a. 1 and 2b. 2 and 3
The test charge is doubled when at 2
a. how does the force change?b. how does the electric field change?
2x
Stays the same
3 larger1 larger