Two identical conducting spheres, fixed in space, attract each other with an electrostatic force of `0.108 N` when separated by `50.0 cm`, centre-to-centre. A thin conducting wire then connects the spheres. When the wire is removed, the spheres repel each other with an electrostatic force of `0.0360 N`. What were the initial charges on the spheres?

Options

A. `pm5xx10^(-6)C` and `pm15xx10^(-6)C`
B. `pm1.0xx10^(-6)C` and `pm3.0xx10^(-6)C`
C. `pm2.0xx10^(-6)C` and `pm6.0xx10^(-6)C`
D. `pm0.5xx10^(-6)C` and `pm1.5xx10^(-6)C`

Answer

B

Explanation

Let charges be `q_1 and -q_2 0.108= (kq_1q_2)/r^2 ` on each `(K.(q_1-q_20)^2/(4r^2)=0.036 implies (q_1-q_2)=2 times 10^-6`
On solving ,`q_1= 3 times 10^-6 and q_2=1 times 10^-6 C`.