Magnetic field Calculation of a Square Wire Loop (with a changed segment)

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
1 replies · 2K views
Physicslearner500039
Messages
124
Reaction score
6
Homework Statement
In Fig. 29-58, length a is 4.7 cm (short) and current i is 13 A. What are the (a) magnitude and (b) direction (into or out of the page) of the magnetic field at point P?
Relevant Equations
No equations from the problem
B2.JPG
I tried to solve the above i have one confusion here.
I have marked the areas as shown
B2_sol.JPG


B2 = B4 = 0;
B1 , B5 Out of Page ; B3, B6 Into the Page.
B1 and B5 Calculation
Now main doubt is regarding the B field of the finite wire let us say 1. I took the derivation of the infinite wire as below from the textbook
B2sol1.JPG

Now instead of integrating from 0 to ∞ for 1, I integrated from 0 to 2a?

B1 = (μ *13)*[(2*a)/(2*√2*a)]/(2*π*2*a); Where R replaced with 2a
B1 = 19.5uT
Similarly for B5 = 19.5uT
Net field out B1 + B5 = 39.1uT
B3 and B6 Calculation
The same equation as above but integrated from 0 to a?
B3=B6 = (μ *13)*[a/√2*a]/(2*π*a); here i replaced R with a
B3=B6= 39.1; Net field into the paper B3+B6 = 78.2 uT

Hence the final field into the paper is = 78.2 - 39.1 = 39 uT;
I have doubts on the integrals of 0 to 2a and 0 to a is it correct? The answer is not matching it is 20uT and into the paper. Please advise.
 
on Phys.org
For the infinite line you have

1579284172285.png


It might be better to rewrite this as ##\large B = \frac {\mu_0 i}{4 \pi}\int_{-\infty}^{\infty} \frac{R ds}{(s^2+R^2)^{3/2}}##

How would this be modified for a finite length?
 
  • Like
Likes   Reactions: Physicslearner500039