Answer:
Charge on the sphere is [tex]2.48*10^{-9} C[/tex]
Explanation:
distance apart r = 5 m
force of repulsion F = 20 N
The spheres had opposite unequal opposite charges, this means that on bringing them into contact, the sphere with the greater charge will have its charge cancel out the other charge on the other sphere. The resultant charge will then be evenly distributed between the two spheres. The result is that both spheres will now have like, equal amount of charge on them.
applying Coulumb's law,
[tex]F = \frac{kQ^{2} }{r^{2} }[/tex]
where
[tex]k = 9*10^{9} m^{3} s^{-4} A^{-2}[/tex]
substituting values into the equation, we have
[tex]20 = \frac{9*10^{9}*Q^{2} }{5^{2} }[/tex]
[tex]Q^{2} = \frac{20*25}{9*10^{9} }[/tex] = [tex]6.17*10^{-18}[/tex]
[tex]Q = \sqrt{6.17*10^{-18} }[/tex] = [tex]2.48*10^{-9} C[/tex]
