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

The wires below are infinitely long and some of them are with loops and semi loops. The current I is constant. What is the magnetic field in point O, when R is the distance from it?

Questions:

In F, E and H, the magnetic field exerted by the terminal infinitely long wire is 0 because it is 180 degrees?

If the loop is a semi-circle, I use B/2? If the loop is a quarter of a circle, then B/4 and so on?

How to solve for G?

**2. Relevant equations**

B= μI/2R

B=2μI/4piR

**3. The attempt at a solution**

I included in my calculations the magnetic fields of both the infinite wire and the loop.

A: μI/2R Outwards

B: μI/2R + 2μI/4piR Outwards

C: μI/2R – 2μI/4piR Outwards

D: μI/2R – μI/2R +2μI/8piR = 2μI/8piR Inwards

E: 2μI/8piR Inwards

F: μI/2R + 2μI/16piR Inwards

G: ?

H: μI/2R + 2μI/8piR + μI/2R Inwards

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