Electric Field- Infinitely long lines of charge

[binbagsss]

Two very long uniform lines of charge are parallel and separated by 0.3m. Each line of charge has charge per unit length: +5.20*10^-6. What is the magnitude of the force that one charge exerts on a 0.0500m section of the other line of charge?

My Attempt

Standard formula for the E field of an infinite line charge is :λ /2πΣσr

F=E*Q
E = 5.20*10^-6/2π*8.85*10-12*0.3
Q(of this section)= 5.20*10^-6*0.05

=> F = EQ = 0.0810 N

However the correct answer is , 4.05*10^-3 N

Cheers Guys =]

 

[jehan60188]

http://theory.uwinnipeg.ca/physics/mag/node10.html

current induces magnetic field
B = uI/(2*pi*r)
the force experienced by a moving charge is IxB
F = IxB
that current crossed with magnetic field
so the current from 1 is crossed with the current from 2