# Electric Field between two charged plates

1. Jan 9, 2016

### ft92

1. The problem statement, all variables and given/known data
Two large, parallel, conducting plates are 7.5 cm apart and have charges of equal magnitude and opposite sign on their facing surfaces. An electrostatic force of 1.3 × 10-15 N acts on an electron placed anywhere between the two plates. (Neglect fringing.)

Find the magnitude of the electric field at the position of the electron

2. Relevant equations
E= F/q

3. The attempt at a solution
Hi, my question is: Can I solve the problem by simply considering the plates large and close enough to make the Electric field between them uniform and apply E= F/q to find the electric field? that is:

E= 1.3 x 10-15/1.67 x 10-19 = 7.78 x 103 N/C ?

It feels like i'm ignoring the information of the distance...

2. Jan 9, 2016

### Staff: Mentor

Usually when a problem says that something is "large" without saying exactly how large, it's meant to imply that a simplifying assumption can be made. In this case it means that you can treat the electric field as being uniform as you suggested.

You'll want to check the value you've used for the charge on an electron

3. Jan 9, 2016

### ft92

Ok, if I use for the charge of the electron -1.602 x 10-19 i get : 1.3 x 10-15/ -1.602 x 10-19= -8.11x 10-3 N/C correct?

Last edited: Jan 9, 2016
4. Jan 9, 2016

### Staff: Mentor

That looks better

5. Jan 9, 2016

### ft92

actually without the minus sign because I'm asked for the magnitude only