Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k...
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Transcript of Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k...
![Page 1: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/1.jpg)
Action at a Distance
Physics 100
Chapt 12
+ -
![Page 2: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/2.jpg)
Coulomb’s law
q1
M1
q2
M2r
Fc = kq1q2
r2
FN = Gmemp
r2
Newton’s law of Gravitation
All possible
distances!
![Page 3: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/3.jpg)
Moon-earth
FN=GMMME
r2
How does the Moonknow that the Earth
is where it is (& what ME is)?
![Page 4: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/4.jpg)
Electroscope
How do the electronsin the foil know thatsomeone is moving a charged object up here?
& that it’s negativelycharged?
& how much it ischarged by?
![Page 5: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/5.jpg)
Ball on an empty trampoline surface
The ball feelsno net force
![Page 6: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/6.jpg)
Ball on a “loaded” trampoline surface
The ball is “attracted” to the girl’s force
![Page 7: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/7.jpg)
Luminiferous aether & E-Fields
+
![Page 8: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/8.jpg)
Faraday’s method for computingE fields
+
Imaginary small positive “test” charge qtest
Ftest=coulomb force on test charge
Ftest
E = Ftest/qtestx+
![Page 9: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/9.jpg)
Example
+ +
![Page 10: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/10.jpg)
E-field from 2 plus charges
![Page 11: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/11.jpg)
E-Field is the dir of force on + charge
+ -
![Page 12: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/12.jpg)
E-Field for opposite charges
![Page 13: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/13.jpg)
Better picture
+
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![Page 14: Action at a Distance Physics 100 Chapt 12 + -. Coulomb’s law q1q1 M1M1 q2q2 M2M2 r F c = k q1q2r2q1q2r2 F N = G mempr2mempr2 Newton’s law of Gravitation.](https://reader036.fdocuments.us/reader036/viewer/2022062313/56649d645503460f94a46c20/html5/thumbnails/14.jpg)
RulesE-field lines start on + charges and end on - charges
Direction of E-field lines = direction of force on a + charge placed at that point (opposite for – charge)
Where E-field lines are close together, the E field is large; where they are far apart, the E-field is small.