What are the total charge and electric dipole moment of the system A system has two charges qA = 2.5 × 10−7 C and qB = −2.5 × 10−7 C located at points A: (0, 0, − 15 cm) and B: (0, 0, + 15 cm), respectively.

Question 9:

A system has two charges q_A = 2.5 × 10⁻⁷ C and q_B = −2.5 × 10⁻⁷ C located at points A: (0, 0, − 15 cm) and B: (0, 0, + 15 cm), respectively. What are the total charge and electric dipole moment of the system?

Solution:

we have tio 

Given that

q_A = 2.5 × 10⁻⁷ C

q_B = −2.5 × 10⁻⁷ C

A: (0, 0, − 15 cm)

B: (0, 0, + 15 cm),

The value of x and y coordinate is zero in both points A and B

So both points are in straight line

And the distance between both points is  = 15 – (-15) = 30 cm = 0.30 m

Total charge of the system will

q = q_A + q_B

= 2.5 × 10⁷ C − 2.5 × 10⁻⁷ C

= 0

The formula of electric dipole moment of the system

p  = charge × d

    = q_A × d

    = 2.5 × 10⁻⁷ × 0.3

    = 7.5 × 10⁻⁸ C m

In this problem negative charge is along positive z-axis

Answer

7.5 × 10⁻⁸ C m along positive z−axis.