How can l calculate the no of constraints?

2.4×10⁻⁵ C

Explanation:

From coulomb's law,

F = kqq'/r² Equation 1

Where F = force on each charge, q = magnitude of the first charge, q' = magnitude of the second charge, r = distance between both charges, k = coulomb's constant.

From the question,

q' = 2q

Therefore,

F = 2kq²/r² Equation 2

make q the subject of the equation

q = √(Fr²/2k) Equation 3

Given: F = 65 N, r = 40 cm = 0.4 m.

Constant: k = 9×10⁹ Nm²/C²

Substitute this values into equation 3

q = √[(65×0.4²)/(2×9×10⁹)]

q = √(5.78×10⁻¹⁰)

q = 2.4×10⁻⁵ C