Helix Angle or Pitch Angle for this Solenoid carring Current?

[magiladd]

Homework Statement

A wire is wound in a helix of pitch angle alpha on the surface of a cylinder of a radius a so that N complete turns are formed. Find the Vector Potential if a current I runs through it.

Relevant Equations

You see, I don’t know the equation, which is the problem.

I honestly have such a dumb question- it says “a pitch angle” but cannot find that in relation to a helix. It is not defined in the textbook. Looking on google I found a helix angle, but is that different than the pitch angle? Can anyone draw me a picture of where the pitch angle is?

I assumed it was the angle from the axis to the difference in height between one turn. I do not know if it should be the angle from the opposite turn to the difference in these turns. Does that make sense? If I were to draw a triangle, I would write that the opposite is the difference in heights of the helix, and the adjacent was the radius. I believe that was wrong too.

If anyone can help me figure out what this picture even looks like, or if the angle is from one side of the helix or the axis, or if you can tell me what a pitch angle is that would be great!

Thank you!

 

[berkeman]

http://www.expertsmind.com/topic/cl...gs/spring-subjected-to-axial-load-915517.aspx

 

[Steve4Physics]

Various definitions may exist. Here's one.

Diagram showing pitch angle:
https://abhinaymishrablog.files.wordpress.com/2016/11/9.png?w=1400&h=9999
which comes from here
https://abhinaymishrablog.wordpress.com/2016/11/07/helical-sweep/

If $p$ is the pitch, $a$ is the cylinder's radius (so cylinder's circumference = $2\pi a$) and the wire has negligible thickness then
pitch angle $\alpha= tan^{-1}(\frac {p}{2πa})$

 

[berkeman]

Diagram showing pitch angle:
https://abhinaymishrablog.files.wordpress.com/2016/11/9.png?w=1400&h=9999

Yikes! That is confusing, having different ways of labeling the pitch angle. So I guess the OP will have to find some diagram or ask the professor.

It is not defined in the textbook.

 

[Steve4Physics]

Yikes! That is confusing, having different ways of labeling the pitch angle. So I guess the OP will have to find some diagram or ask the professor.

If the OP can't get the 'official' required definition, I'd suggest stating whatever definition is preferred and then running with that.

The various possible definitions should all be simply related, so choice of definition is (hopefully) not a big deal.