Does NH2- have a dipole moment and how do you know

Thanks.

yes it does
NH2- has 3 electrons that are not bound to any other element

••
N¯ --H
H
the extra, unbound electron adds to the dipole of NH3 already present with the nonbonding pair of electrons already present

Yes.

Looking at the periodic table, nitrogen will want to have three bonds. NH2 only has two bonds, leaving the molecule with a lone pair and a negative charge. Since the molecule is charged, it will have a dipole moment and the electron density will be on the nitrogen.