1. PHY 2049: Physics II
Tutoring Center is open in room NPB 1215, M-F 12:00AM -4:00PM. It is free.
Hopefully all Wiley Plus problems have been
solved. Please see me immediately after the class if there is still an issue.

2. PHY 2049: Physics II
About bicycle riding: If some one shows you a trick, it means that,
It is possible to do that trick
The person who showed you, can do the trick.
It does not mean that you can do the trick.
Try it a lot of times and you can too.

3. Electric fields from different geometrical objects.
wires
Rings and disks
Planes
Another algorithm Al-Khwarizmi the Persian astronomer and mathematician, wrote a treatise in Arabic in 825 AD, On Calculation with Hindu Numerals, which was translated into Latin in the 12th century as Algoritmi de numero Indorum[1], which title was likely intended to mean "Algoritmi on the numbers of the Indians", where "Algoritmi" was the translator's rendition of the author's name; but people misunderstanding the title treated Algoritmi as a Latin plural and this led to the word "algorithm" (Latin algorithmus) coming to mean "calculation method". The intrusive "h" is most likely due to a false cognate with Greek αριθμος arithmos = "number".
(wikipedia:

4. PHY 2049: Physics II
Flux and Gauss’ theorem

5. PHY 2049: Physics II Gaussian (imaginary) surfaces Flux = Φ = ∑ E.dA
E.dA for a cube is easy to visualize.
Let calculus do it for a sphere or any other shape.
Φc = qtotal /εo

6. S1: Φc = q/ εo
S2: Φc = -q/ εo
S3: Φc = 0
S4: Φc = 0

7. For a cylinder with axial field, no contribution to flux from the side walls.
From the far top, >0
Near (bottom) , <0

8. PHY 2049: Physics II No force/field from the charge outside
On inside circle E.4πr2=q/εo Coulomb’s law
Very outside, E = k 5q/r2 P + + + + + +

9. PHY 2049: Physics II The electric field in a metal is zero
Charge +q on inside surface.
Because it is neutral, outside surface must be -q.

10. PHY 2049: Physics II Electric field is radial.
E.A = 0 for the top and bottom surfaces.
Sideways:
E 2πrh = λh/ε0
E = λ/ 2πrε0

11. PHY 2049: Physics II
Plane
2EA = σA/εo
E = σ/2εo

12. PHY 2049: Physics II
E = σ/εo inside

14. PHY 2049: Physics II Gauss’ theorem
Electric fields due to a point charge (Coulomb’s), a wire and a plane.
Charge shells don’t act inside.
In an insulator with uniformly distributed charge, only charge enclosed contributes to the field.