Answer:
1 N
Explanation:
Given that two point charges +3 micro coulomb and +8 micro coulomb repel each other with a force of 40N.
Let us first calculate the distance between the two point charges
F = (KQq)/r^2
Where K = 9.0 × 10^9Nm^2C^-2
40 = (9×10^9 × 3×10^-6 × 8×10^-6)/r^2
Make r^2 the subject of formula
r^2 = 0.216/40
r = sqrt (5.4^-3)
r = 0.0735 metres
If a charge of -5 micro coulomb is added to each of them, then the force between them will become?
Using the same formula again
F = ( KQq)/r^2
Where Q = 8 - 5 = +3 × 10^-6 C
q = 3 - 5 = - 2 × 10^-6 C
F = ( 9×10^9 × 3×10^-6 × 2×10^-6 )/5.4×10^-2
F = 0.054/0.054
F = 1 N
The force of attraction between the two point charges will be 1 N
