1.
7. A metal sphere with a hollow center has a charge of -2q, initially all on the outer surface. An
additional charge of +q is placed in the hollow center of the sphere. The charge on the outer
surface of the sphere becomes: (Draw electric lines of field clearly.)
Solution
If a charge Q hollow is given in cavity of conductor than it will induce - Q hollow on inner wall of
cavity and Q hollow on outer surface of cavity
So
+q will be added to outer surface of conductor
HEnce net charge onouter surface of metal sphere
Q= -2q+q = -q
Electric field will be radially outward in cavity But radially inward outside the sphere .
in the vicinity of sphere No field will be present