# Magnetic flux of Earth

1. Oct 25, 2008

### goWlfpack

Magnetic flux!!!!

1. The problem statement, all variables and given/known data
Find the flux of Earth's magnetic field of magnitude 5.00 10-5 T through a square loop of area 40.0 cm2 for the following:
(a) when the field is perpendicular to the plane of the loop

(b) when the field makes a 20.0° angle with the normal to the plane of the loop

2. Relevant equations

flux = BA cos theta
where A is the area and B is the magnetic field

3. The attempt at a solution
on the first one i just multiplied 5e-5 by .4 and i got 2.0e-5... and it was wrong and i have NO idea why

the second one i just used the answer i got previously (obviously wrong) and multiplied it by cos of 20... red x
HELP!

2. Oct 25, 2008

### borgwal

Re: Magnetic flux!!!!

You have to convert cm^2 to m^2 in the correct way

3. Oct 25, 2008

### goWlfpack

Re: Magnetic flux!!!!

the correct way? its not directly proportional?

4. Oct 25, 2008

### borgwal

Re: Magnetic flux!!!!

It's directly proportional, but not with the proportionality constant you think!

You seem to think that 40 cm^2 equals 0.4 m^2. That's not true!