# Magnetic field strength

griercorleone

## Homework Statement

I got 1/2 of this problem right, but I am not sure of the other part. I have attached the picture. The questions are as follows (with the answers that I am sure of) --

What is the magnetic field strength at point 1 in the figure?
What is the magnetic field direction at point 1 in the figure? (out of the page)
What is the magnetic field strength at point 2 in the figure?
What is the magnetic field direction at point 2 in the figure? (in to the page)
What is the magnetic field strength at point 3 in the figure?
What is the magnetic field direction at point 3 in the figure? (out of the page)

## Homework Equations

B = permeability constant * I/ 2(pi)r

## The Attempt at a Solution

Well, for the first one example, this is what I did.

(1.257*10e-6)*(10)/2(pi)(.02m) = 1*10e-4

This is not correct however? Can someone give me some instruction? And for the second and third ones, which wire am I calculating from?

#### Attachments

• 12.jpg
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## Answers and Replies

Homework Helper
You calculated the field induced by one wires, but there are two wires in the diagram. You have to figure out what direction the field induced by each wire is and add or subtract accordingly.