Electric Field and potential of spherical shell

[YoungILoveYou]

A charge punctiform of $$Q= 12*10\exp-6 C$$ is in the center of a spherical shell conductor charged negatively $$Q1= 6*10\exp-6 C$$, and of internal radius = 22 cm ad external=26 cm.
Calculate the electric field and potential.

 

[siddharth]

What are your thoughts/ideas on this problem? You need to show some work before you get help.

 

[YoungILoveYou]

My reasoning is:

Ri=Internal radius
Re=External radius
$$E int= 1/4\pi\epsilon_0 * Q/Ri^2$$
$$E ext= 1/4\pi\epsilon_0 * Q1/Re^2$$

and then use

$$V=\int E dl$$

What do you think?

edit
I correct something

 

[Tomsk]

First off, it should be 1/r² not 1/r. Shoudn't E_int be for a general point 0<r1<Ri, and E_ext for Re<r2<infinity, or are you calculating the field strength at those points? I don't see why else they'd give you the size of the charge and of the radii. Also, you need to consider the total charge inside your general sphere of radius r2, not just the charge on the metal sphere.

 

[YoungILoveYou]

are you calculating the field strength at those points? I don't see why else they'd give you the size of the charge and of the radii. Also, you need to consider the total charge inside your general sphere of radius r2, not just the charge on the metal sphere.

For the precision the problem demands E(r) and V(r).
Perhaps I have not understood well what I must calculate.