# PhysicsDeriving Y-component of uniform electrical rod from its electric potential formulae.

#### Quintessential

##### New member
This is essentially the problem.

And this is what I did.

Realizing the following:

E = -▽V

I simply took the derivative in regards to the vertical component, in this case "a".

So:

-dV/da [the above formulae]

And I got the following:

Κλl/(a sqrt(l^2+a^2))

**Sorry, I have no idea on how to operate the sexy mathjax characters.

#### Klaas van Aarsen

##### MHB Seeker
Staff member
This is essentially the problem.

And this is what I did.

Realizing the following:

E = -▽V

I simply took the derivative in regards to the vertical component, in this case "a".

So:

-dV/da [the above formulae]

And I got the following:

Κλl/(a sqrt(l^2+a^2))

$$E_y = \frac{k_\ell Q}{y \sqrt{\ell^2 + y^2}}$$