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Couple More Questions on Electrostatics

1. Homework Statement
1) From the observation that there's an electrostatic attraction between object A and B, what's the most you can conclude about the electric charge on A and B?

2) A plastic sphere with a positive charge of 4.8E-19 C is held stationary in a gravitational field of strength 9.8m/s/s by an electric field of strength 1.2E5 N/C. What is the force of gravity of the sphere?

3)How did Benjamin Franklin define a negative charge?

4) Draw a diagram to show the lines of force around a small positive charge.

5) Point P is 3.0 cm away from a small object with a positive charge of magnitude 5.0 muC. What is the electric field strength at point P?
2. Homework Equations
F=QE
F=kQq/d^2


3. The Attempt at a Solution
1) One has to be positive and one has to be negative.

2) 1.2E5 N/C=Fg/4.8E-14 N
Fg=5.8E-14 N

3) He defined it as having more electrons than protons.

4)
positive.jpg


5) QE=(kQq)/r^2
E=(kq)/r^2
E=[(9.0E9)(5.0E-6 C)]/(0.030m)^2
E= 5.0E7 N/C
 

berkeman

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In the diagram, remember that the lines of the electric field (and hence the lines of force) originate on + charges and terminate on - charges. How would that change your drawing some?
 
you mean drawing the lines out of the positive charge?
 

berkeman

Mentor
55,886
5,946
you mean drawing the lines out of the positive charge?
Maybe....

There would be two cases, with variations on those two cases, right? The first would be a simple diplole, where there are two equal charges spaced apart. What would the E field distribution (and therefore the force vector field) look like for that?

The second case is a positive charge embedded in an overall E field that is generated by something external (like a positive ion sitting between the plates of a capacitor). How would that change the E field diagram?
 

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