# Find the electric dipole moment for a water molecule

## Homework Statement:

Find the electric dipolar moment for a water molecule using the definition of the dipolar moment, after that find the electric field needed to move this molecule.

## Relevant Equations:

p = ∫ r' ρ(r') dV'
The equation that we saw in class is for a continuous charge distribution, I think that for this exercise I need to treat the system as a discrete charge distribution but I'm not sure. Also, I don't know how I can calculate the intensity of the electric field needed to move this charge.

## Answers and Replies

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It all depends on how you model a water molecule. You may model it a linear molecule and apply defination(Crudest case) or you may go and use actual model of molecule and using the fact that dipole moments are vectors.

To answer your first question,the integral can be easily converted into sum:

$$\mu= \sum_{I} q_i r_i \hat r$$

Where $r_i\text{'s}$ are the position vectors from a suitable fixed origin.