Three tiny charged metal balls are arranged on a straight line. The middle ball is positively charged and the two outside balls are negatively charged. The two outside balls are separated by 20 cm and the middle ball is exactly halfway in between. (HINT: Draw a picture; in your picture, the distance between the two outermost balls should be 20 cm.) The absolute value of the charge on each ball is the same, 1.45 μCoulombs (the meaning of μ, which is read as "micro", is 10-6). Give your answers in newtons.

, and .

Explanation:

Three balls are shown in figure having charge . The middle ball, , is positively charged having charge , and the remaining two outside balls, and , are negatively charged having charged as shown.

and cm as B is the mid-point of AC.

Let and

From Coulomb's law, the magnitude of the force, , between two point charges having magnitudes , separated by distance, , is

where, is the permittivity of free space and

in SI units.

This force is repulsive for the same nature of charges and attractive for the different nature of charges.

Now, Using equations(i),

(a) The magnitude of attraction force between balls A and B is

(a) The magnitude of the repulsive force between balls A and C is

(c) The magnitude of the net force, , on the outside of the ball is,

1/0.14nm = 10^10/1.4 a lot