Two insulated metal spheres of raddi 10 cm and 15 cm charged to a potential of 150 V and 100 V respectively, are connected by means of a metallic wire. What is the charge on the first sphere?

Options

A. 2 e.s.u.
B. 4 e.s.u.
C. 6 e.s.u.
D. 8 e.s.u.

Answer

B

Explanation

Here, `r_(1) = 10 cm, r_(2) = 15 cm`
`V_(1) = 150 V, V_(2) = 100 V`
Common potential
`V = (C_(1)V_(1) + C_(2)V_(2))/(C_(1) + C_(2)) = (4pi epsilon_(0)(r_(1)V_(1) + r_(2)V_(2)))/(4pi epsilon_(0)(r_(1) + r_(2))) = 120` volt
`q_(1) = C_(1)V = 4pi epsilon_(0)r_(1)v = (10^(-1))/(9 xx 10^(9)) xx 120 C`
`= (12)/(9 xx 10^(9)) xx 3 xx 10^(9)` e.s.u. = 4 e.s.u.