A system has two charges `q_(A)= +2.5xx10^(-7)C and q_(B)= +2.5xx10^(-7)C` located at point A: (0,0,-15 cm)and B: (0,0,+15 cm)`, respectively. What are the total charge and eletric dipole moment of the system?

Options

A. `0` , `0`
B. `7.5 xx 10^-8 C` , `7.5 xx 10^-8 Cm`
C. `7.5 xx 10^-8 C` , `0`
D. `0` , `7.5 xx 10^-8 Cm`

Answer

D

Explanation

The two charges `q_(A)` and `q_(B)` are equal and opposite and situated a fixed distance apart, from an electric dipole. Thus the charge of the system is
`q_(A)+q_(B)=2.5xx10^(-7)C - 2.5xx10^(-7)C=0`
The distance between the two charges is `2a=30cm=0.3m`. So the dipole moment of the system is either charge`xx2a`
`=(2.5xx10^(-7)C)(0.3cm)=7.5xx10^(-8)Cm`
The direction of `vec(p)` as shown in fig. is from B to A, i.e. along the negative z-axis.