The change of color. Each color has a different wavelength therefore a different frequency.
Answer:

Explanation:
According to the free-body diagram of the system, we have:

So, we can solve for T from (1):

Replacing (3) in (2):

The electric force (
) is given by the Coulomb's law. Recall that the charge q is the same in both spheres:

According to pythagoras theorem, the distance of separation (r) of the spheres are given by:

Finally, we replace (5) in (4) and solving for q:

Answer:
a luminous ball of plasma
Here, as the charge is uniformly distributed in the sphere, we will consider s as an area of the sphere which is, s=4πr2 and r is radius of the gaussian surface shown in the figure above. From this, it can be seen that