Question

Two identical coils are parallel to each other on the same axis. They are separated by a distance equal to their radius. They each have N turns and carry equal currents I in the same direction. Calculate the field strength on the axis at the midpoint between the two loops if the loops are 10 cm in diameter, have 10 turns, and carry a current of 1.0 A

This just equates to zero doesn't it? Since the current is going in the same direction wouldn't the field strength at the midpoint between coils be zero?

Answer 1

You want Electric field strength? Not magnetic?

Answer 2

No it's definitely magnetic field I'm looking for in this question.

Answer 3

Well right off the bat then "I cans so no, the fields will not cancel they will add if the currents are both moving in the same direction, say counterclockwise. Using the right hand rule we can see that both wires will produce and upward B field, which will add, not cancel.

Answer 4

I can say "no ^^^

Answer 5

So do I just find the magnetic field of the two coils and add them together or is there some tricky business involving the midpoint?

Answer 6

there is a name for this setup, I am looking up the info from OCW right now...

Answer 7

Well you can at least find the field with the Biot-Savart law. Look at example 9.2 on this page. Notice the equation for the z-component. Those will add in your setup.
http://ocw.mit.edu/courses/physics/8-02sc-physics-ii-electricity-and-magnetism-fall-2010/magnetic-field/MIT8_02SC_notes16to18.pdf

Answer 8

I believe there is another equation that will work faster and is customized to this situation, but I could not find it offhand and am a bit busy at the moment.

Answer 9

No problem at all. You're help has been great so far. I'm sure I'll be able to work something out from what you've told me. Thanks a billion. :)

Answer 10

anytime, glad it helped :)