Consider two point charges `q_1 and q_2` at rest as shown in the figure.

They are separated by a distance of 1m. Calculate the force experienced by the two charges for the following cases:
`q_1 = + 2 mu C and q_2 = -3 mu C` kept in water `(epsilon_(t) = 80)`

Explanation

If these two charges are kept inside the water, then the force experienced by `q_2` due to `q_1`
`vec(F)_(21)^(W) = (1)/( 4pi epsilon) (q_1 q_2 )/( r^2) hat(r)_(12)`
since `epsilon = epsilon_(r) epsilon_(o)`,
we have `vec(F)_(21)^(W) = (1)/(4pi epsilon_(r) epsilon_(o) ) (q_1 q_2)/( r^2) hat(r)_(12) = (vec(F)_(21))/( epsilon_(r) )`
Therefore,
`vec( F)_(21)^(W) = - ( 54 xx 10^(-3) N)/( 80 ) hat(i) = - 0.675 xx 10^(-3) N hat(i)`