
#1
Jan307, 12:13 AM

P: 164

1. The problem statement, all variables and given/known data
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 4.8E19 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. Relevant 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/4.8E14 N Fg=5.8E14 N 3) He defined it as having more electrons than protons. 4) 5) QE=(kQq)/r^2 E=(kq)/r^2 E=[(9.0E9)(5.0E6 C)]/(0.030m)^2 E= 5.0E7 N/C 



#2
Jan307, 10:23 AM

Mentor
P: 39,601

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?




#3
Jan307, 10:48 PM

P: 164

you mean drawing the lines out of the positive charge?




#4
Jan407, 12:51 AM

Mentor
P: 39,601

Couple More Questions on ElectrostaticsThere 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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