# Homework Help: Magnetic Flux Density

1. Mar 16, 2010

### ryukyu

A 1mm-diameter copper wire is shaped into a square loop of side = 4cm. It is placed in a plane normal to a magnetic field increasing with time as $$\vec{B}$$=1t$$\hat{z}$$Wb/m2. Calculate the magnetic flux density at the center of the loop.

I found that the magnitude of the induced current is 0.456 A

3. The attempt at a solution

I know that H will be in -z direction

B=4$$\mu$$0H

H=?

2. Mar 16, 2010

### rl.bhat

You have found the current in the square. Now find the field at the center of the loop due to each segment of the square. According to Lenz's law this field must be in opposite direction to the applied field. Hence find the net field.