Electric energy stored in dipole

[mbmcgee]

there is a +q and -q on the x-axis. the +q is L/2 in the negative direction and the -q is L/2 in the positive directions. the distance between the two charges is L. there is a test charge P on the y-axis a distance r from both charges.

we had to find the electric energy stored in the dipole.

she gave us the answer -> W= (q^2)/(4*pi*epsilon_0*L) => W=(q_1*q_2)/(4*pi*r_12)

i do not understand how she got this. could someone please enlighten me a little bit?
thanks

 

[Hootenanny]

there is a +q and -q on the x-axis. the +q is L/2 in the negative direction and the -q is L/2 in the positive directions. the distance between the two charges is L. there is a test charge P on the y-axis a distance r from both charges.

we had to find the electric energy stored in the dipole.

she gave us the answer -> W= (q^2)/(4*pi*epsilon_0*L) => W=(q_1*q_2)/(4*pi*r_12)

i do not understand how she got this. could someone please enlighten me a little bit?
thanks

You can calculate the potential energy of the dipole the same way in which you calculate the potential energy of any array of charges.