# Homework Help: Magnetic Field at center of circle on rectangular circuit

1. Feb 21, 2012

### soccerscholar

1. The problem statement, all variables and given/known data

A circuit consists of 7 sections of wire. The figure looks like a rectangle of length 9cm and width 5cm with a circle of diameter 3 cm cutting right through the middle of one of the 9cm sides so that the two sides of the circle are in parallel. Each of the sections of wire also has a resistance. I am supposed to find the magnetic field at the center of the circle using symmetry.

3. The attempt at a solution
So I figured out the current based on the givens, but how do I find the magnetic field at the center of the circle using this? Which current would I use in the equation for magnetic field of a circular loop (Bcircular loop- see above), would I use the current of the rectangle part of the circuit, or one of the currents in the circle? How do I factor in the effect of the rectangle when I calculate the magnetic field at the center of the circle? Thanks for any help, I just need guidance and hopefully I'll be able to figure it out from there.

2. Feb 21, 2012

### vivekrai

It be better if you substitute your so lengthy question with a small figure and a reasonable question. Point out the exact matter of doubt instead of writing this and that. It makes more sense then.