Find a point charge a distance form a charged rod

[rocapp]

Homework Statement

See image

Homework Equations

KQ/r^2

The Attempt at a Solution

I have seen several different ways of working this problem, but they have all failed on me.

I tried this using the equation above from my book

E = (8.99x10^9)(1036 C)/(4x10^-6m)

E= 2.328x10^18 N/C

I also tried using

E = K*Q/sqrt(r^2+(L/2)^2)
E = 1.86x10^11 N/CThis was not correct. Please help. Thanks in advance!

 

[ehild]

Read the problem text. You have to find the electric field at a distance from the rod (not a point charge).

See http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elecyl.html

ehild

 

[rocapp]

Thanks! The answer is 5.3x10^13N/C

 

[ehild]

Correct.

ehild