Two identical small conducting spheres having unequal positive charges `q_1` and `q_2` are separated by a distance r. If they are now made to touch each other and then separated again to the same distance, the electrostatic force between them in this case will be

Options

A. less than before
B. same as before
C. more than before
D. zero

Answer

C

Explanation

`F_1=(kq_1q_2)/r^2` `(k=1/(4piepsilon_0))`
`F_2=(kq_1^'q_2^')/r^2`
where, `q_1^'=q_2^'=(q_1+q_2)/2`
`:. F_2=(k(q_1+q_2//2)^2)/r^2`
`((q_1+q_2)/2)^2gtq_1q_2`
This is because
`(q_1+q_2)^2=(q_1-q_2)^2+4q_1q_2`
or `(q_1+q_2)^2gt4q_1q_2`
or `((q_1+q_2)/2)^2gtq_1q_2`
`:. F_2gtF_1`