Calculating the Dipole moment of an insulator in an electric field I know that the dipole moment equation is $p = qd$, but when I looked at videos and articles, they only talked about polar molecules. If I put an insulator for example co2 in an electric field, what will be the dipole moment?
 A: Perhaps, such situations fall in concept of dielectrics. These are substances which don't have free electrons, or in other words are non-polar substances. They often don't have fixed dipole moments in absence of eletctric field

Here, we can see in absence of electric field, the dipole moments of individual molecules are randomly arranged (if present at all).
After applying a constant electric field, the molecules' become polarised and their dipole moments also becomes fixed  and arranged in the direction of field lines.
Here we are more interested by finding polarization vector $\vec P$ which is defined as dipole moment per unit volume.
Lets take, a rectangular  box containing dielectric substance, with constant applied electric field. Let its area of corss section be $A$ and length $\ell$.
Now let's say we have induced charge per area (appearing by polarization of dielectric), denoted by $\sigma_A$.
So total charge $q$: $q=(\sigma_A)(A)$
So by definition of polarization vector $\vec P$:  $P=\frac{p}{A\ell}$
,where $p$ is dipole moment. Now:
$$P=\frac{(\sigma_A \cdot A)\ell}{A\ell}$$
Hence finally we get:
$$P=\sigma_A$$
Hope it helped you out.
