Where Is the Net Electric Field Zero Between Two Charged Lines?

Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
1 reply · 4K views
amodedude1
Messages
1
Reaction score
0
1. In the figure below, short sections of two very long parallel lines of charge are shown, fixed in place and separated by L = 8.0 cm. The uniform linear charge densities are +5.8 µC/m for line 1 and -2.0 µC/m for line 2. Where along the x-axis shown is the net electric field from the two lines zero? (link to image: ) http://img190.imageshack.us/img190/8695/hrw72335.gif

L=8cm=.08m
charge density1=+5.8 µC/m
charge density2=-2 µC/m2. I used E1=E2

3. The Attempt at a Solution :

I solve E1=E2

I cancel the 1/(4pi E)'s , cross multiply and get charge density1(x-L/2)=charge density2(x+L/2), then get charge density1/charge density2= (x-(L/2))/ (x+(L/2))

but my very poor algebra limits me here. How do I go about solving this. (remember my algebra is hideous)
 
Last edited by a moderator:
Physics news on Phys.org
The electric field varies as 1/r for a wire? If so we can superimpose the two fields along the x axis,

E(along the x axis) = q_1/x + q_2/(x + separation of lines) = 0

solve for x