A system has two charges qA=2.5×10−7C and qB=−2.5×10−7C located at points A(0,0,-15cm) and B(0,0,+15cm), respectively. What are the total charge and electric dipole moment of the system?
Given A(0,0,-15cm) and B(0,0,+15cm)
qA=2.5×10−7CqB=−2.5×10−7C
The distance between A and B is the length of dipole (because qA and qB are same in magnitude and opposite in nature, so they form a dipole).
AB=2l=length of the dipole
=30cm= 30×10−2m.
The total charge q on the dipole is
q=qA+qB=2.5×10−7−2.5×10−7C=0
The electric dipole moment p= Any charge×Length of the dipole
p=qA×2l=2.5×10−7×30×10−2p=7.5×10−8C−m
The direction of the dipole moment is always from negative charge to positive charge that is along B to A.