# Electric Field Strength Between Two Parallel Plates Problem

**1. The problem statement, all variables and given/known data**

If the electric field strength between two parallel plates 1cm apart is 3.1kN/C, how much energy will be used by the electric field to move an electron (placed half way between the plates) 3mm nearer to the positively charged plate?

**2. Relevant equations**

Work Done = 1/2V^2C

F=KxQ1Q2/r^2

E=KxQ/r^2

E=V/D

**3. The attempt at a solution**

I know that the answer to this question is 1.49×10^-18 J. I feel that I may be going about this question the complete wrong way but this is what I did:

I worked out the potential difference between the plates to be 31V by using the equation V=ED

V=(3.1×10^3)x(0.2×10^-2)—–> I got this value for D by taking away 3mm from the 5mm half way point between the plates.

I then subbed in the values that I know into the equation Work Done = 1/2V^2C

Work Done = 1/2 x 6.2^2 x (1.6×10^-19)

This gave me 3.08×10^-18.

I feel like I’m going the wrong way about this question. Hope someone can help and hope I’ve worded this well enough for you all to understand haha.

http://ift.tt/1efuw1k

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