# Homework Help: Biot Savart Law?

1. Mar 6, 2016

### meaghan

1. The problem statement, all variables and given/known data
A straight wire caries a 10.0−A current (the figure(Figure 1) ). ABCD is a rectangle with point D in the middle of a 1.10−mm segment of the wire and point Cin the wire. Find the magnitude and direction of the magnetic field due to this segment at the following points.

2. Relevant equations
dB = μ*i/4*pi*r ds
B = μ*i*L/4*pi*r

3. The attempt at a solution
to find the magnetic field at A, would i integrate along ds to get to the second equation then plug in the necessary information?

2. Mar 6, 2016

### marcusl

Integrate the first equation over the 1.1 mm length indicated. Use the vector form of the B-S Law to properly capture the geometrical relationship between the current element and the observation points. Your second equation is only valid for the field away from an infinitely long current--not your situation.

3. Mar 6, 2016

### meaghan

okay, so would i get that my radius = 5cm as well?

4. Mar 6, 2016

### marcusl

Well, r is distance (diagonal) from source to observation so it varies.