# proving delta

#### yef smith

Joined Aug 2, 2020
381
Hello i have a current loop with radius "a" (not a small loop).
i have an expression of current density.
I want to verify the expression for J using an integral to get the Current "I",so if i integrate J all over i will get I.
Integral of a function multiplied by delta has a property .

How should i construct the integralpropely to get back I?
using cylindrical coordinates.
z from -int to +inf
pho is from zero to +inf
theta is from zero to 2pi
so if i plug them in you can se in the integral bellow that if we use cylindrical system the integral over J doesnt return "I"
Where did i go wrong constructing the cylindrical integral?
Thanks.

#### Delta Prime

Joined Nov 15, 2019
1,311
Hello there you just had to bring up Delta now I have to answer don't worry I know what I'm talking about .
You are trying to find current because of the closed loop, not because of current density I recall that
J = Current divided by area
You have to integrate J to find I
Is this homework? I don't think you should use Delta if so I need to speak with your instructor. I'll give you a hint from the photo it looks like you're trying to find b not a.