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Preamble:

Review Previous 3 lectures

HW Example 22.59

You have a lightweight spring whose unstretched length is 4.0 cm. First, you attach one end of the spring to the ceiling and hang a 1.4 g mass from it. This stretches the spring to a length of 5.0 cm . You then attach two small plastic beads to the opposite ends of the spring, lay the spring on a frictionless table, and give each plastic bead the same charge. This stretches the spring to a length of 4.4 cm.

Σ F = 0 → F_E = F_sp
F_sp = kΔs → k = F_g/Δs
F_E= (4 πε) ^-1 q²r^-2

HW Example 23.xx

Everyone did well on this chapter.

Blackboard Example

Electric Field of an ∞ long charged rod by Coulomb's Law

Key Points

Flux	Gauss's Law
$$ \Phi = \iint \mathbf E \,\cdot d \mathbf A $$	$$ \Phi_c= \oint \mathbf E \, \cdot d \mathbf A = {Q \over \epsilon} $$

Game Quiz Ch24

Lecture

Symmetry

Slides, Ref 24.1

Flux

Slides, Ref 24.2, 24.3

Gauss's Law

Ref. 24.4

Application

Ref. 24.6

Conductors in Electrostatic Equilibrium

ppt Ref. 24.6