3 dbts..

Q1.

If the outer surface of the outer sphere carries a charge of 10^-9C and its inner surface carries a charge of 0C. So the net potential on the outer sphere is :

9 x 10⁹ x 10⁹ 20

This gives potential as 45 x 10⁶ Volts

Q1//:V=22.5
Q2//:
The electric force will act as centripetal force
let electric field at this position is E,is given by E=mxw²/e
now P.D. across a distance dx at this position is E.dx=mxw²/e *.dx
=>P.D b/w axis and the outer surface iz mrw²/2e
Q3//:cant solving

1) its a multiple of 45 .i think ankur is right