# Three concentric conducting spherical shells carry charges +4Q on the inner shell , -2Q on the middle shell and +6Q on the outer shell . The charge on the inner surface of outer shell is

$(a)\;0\qquad(b)\;4Q\qquad(c)\;-Q\qquad(d)\;- 2Q$

Answer : (d) $\;-2Q$
Explanation :
Charge induced on inner surface of outer shell = -2Q .

edited Aug 11, 2014