# Electric field problems

1. Jan 31, 2010

### kmjones26

I need help getting started on a few questions. If you could just provide the equation I should use then I would be very thankful.

1. A point charge of 2Q is a distance L from a point charge of -Q. What is the electric field at Point P a distance L abouve the center of the 2 charges. Picture below:
<...........>P
<...........>|
<...........>|
2Q______L______-Q

2. What would the force be on a -Q charge placed at the point a distance L above the center of the charges in the problem above.

3. What is the electric field a distance of 0.5 meters above an infinite plain of charge density 25C/m^2

4. If the center of a flat plate wish a radius of 5cm is placed at an angle of π /3 radians, 1 meter above the infinite plain from the previous problem, then what would be the flux through the plate?

5. What would be the electric field a distance R away from an infinite wire with a charge density of λ

2. Feb 1, 2010

### tiny-tim

Welcome to PF!

Hi kmjones26! Welcome to PF!

(try using the X2 tag just above the Reply box )

1. Electric field is a vector, so find the two vectors at P from the two charges, and add the components.

2. Force = charge times electric field (F = qE).

Show us what you get.