# Magnetism question

1. Apr 29, 2007

### Boulderbison19

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

A compas needle points 20 degrees East of North outdoors. However, when it is placed 8cm to the east of a vertical wire inside a building, it points 55 degrees east of north. what is the magnitude and the direction of the current in the wire? the earth's field is 5.0E-5 and is horizontal

2. Relevant equations

Sin=O/H Cos=A/H

B=UI/ 2(pi)R

3. The attempt at a solution

i solved for the horizontal and vertical components of the earths magnetic field and found the components for the x and y to be 4.56E-5 and 2.04E-5 respectively.

i am stuck on how to find the components for the magnetic field of the wire.

any help will be greatly appreciated

2. Apr 29, 2007

### mbrmbrg

What do the magnetic field lines around a wire look like?

3. Apr 29, 2007

### Boulderbison19

there is no diagram, that is all the information given about the problem. i copied the problem word for word out of the book.

4. Apr 29, 2007

### mbrmbrg

You didn't cover magnetic field lines in class? The book doesn't cover them in the section preceding the problem?

5. Apr 30, 2007

### Boulderbison19

it does, but it doesnt cover this type of question.