Among two discs A and B, first have radius 10 cm and charge `10^(_6) -mu`C and second have radius 30 cm and charge `10^(-5)`- C. When they are touched, charge on both `q_(A)` and` q_(B)` respectively will, be

Options

A. `q_(A)=2.75muC, q_(B)=3.15muC`
B. `q_(A)=1.09muC, q_(B)=1.53muC`
C. `q_(A)=q_(B)=5.5muC`
D. None of these

Answer

C

Explanation

When touched charge flows from higher potential to lower potential till equalizes on the two discs.
Given, `" "q_(A)=10^(-6)C, q_(b)=10^(-5)C`
`therefore" "q=(q_(A)+q_(B))/(2)=(10^(-6)+10^(-5))/(2)=5.5muC`