Plot the surface current density in the shell as a function of the measured from the apex of axial coordinate z.

So here is photo and result. I don't understand why are they using perimeter? Why is there tan?
Can someone explain me on easy way because I don't understand anything.

 

This is a shell, right (something like a very thin funnel)? So, at any given height, all of the current is passing through a ring. How long is that ring?

 

This is a shell, right (something like a very thin funnel)? So, at any given height, all of the current is passing through a ring. How long is that ring?

This is not easy explanation. I don't how much is long. I would say it's long like the time that currents flows through it.

 

This is not easy explanation. I don't how much is long. I would say it's long like the time that currents flows through it.

This makes no sense whatsoever.

What is the surface current density (which would be expressed in amperes per inch) if the current is flowing lengthwise through a cylinder that has a diameter of two inches?

 

This makes no sense whatsoever.

What is the surface current density (which would be expressed in amperes per inch) if the current is flowing lengthwise through a cylinder that has a diameter of two inches?

It will be I/Area

 

No, because it is not asking for current density, it is asking for surface current density. So it is I/Length.

 

No, because it is not asking for current density, it is asking for surface current density. So it is I/Length.

But I don't understand why is there tan?

 

What is the circumference of the shell a distance z above the apex? Isn't that a function of the angle of the cone?