Question

Can someone please help me with this question? This is supposed to be fairly simple. I think I am just doing the calculations wrong.
See attachment

Answer 1

I know the answer by the way and I also know that the last figure has a an electric field of 0 so it is the last one in order but what about the first and second rod?

Answer 2

Which order should they go in?

Answer 3

I think I am supposed to use the equation: E= Q/l / 2pi (epsilon 0) r

Answer 4

The order is supposed to be a,b,c but I got b,a,c because the halved length of the rod will cause the the electric field to be greater, so I just want to know what am I doing wrong?

Answer 5

maybe you can try to integrate to get your answer , just ti see the full process
as for your formula ,i am not sure about it
did you use gauss law to find that formula ? the rods are of finite length so you cant use gauss law if you did there

Answer 6

I am taking general physics so I don't use calculus for any question

Answer 7

@Nali You are right, b yields a stronger field than a, because the charges are closer to point P.

Your answer key or the wording of the problem must be wrong.
The answer would have been a > b > c , if the charge DENSITY \(\lambda\) had been the same throughout.

Answer 8

ok thanks @Vincent-Lyon.Fr

Answer 9

so my answer is right a>b>c