Two insulated charges conducting spheres of radii 20 cm and 15 cm respectively and having an equal charge of `10 mu C` are connected by a copper wire and then they are separated . Then
(1) Both spheres will have equal charges.
(2) Surface charges density on the 20 cm sphere will be greater than that on the 15 cm sphere
(3) Surface charge density on the 15 cm sphere will greater than that on the 20 cm sphere
(4) Surface charge density on the two spheres will be equal.

Explanation

Answer (3)
After touching , potential will be same on both
`:. U = (sigmar)/(epsilon_(0)) = ` constat
then `sigma r = ` constant
`sigma prop (1)/(r )`
So , sphere of radius 15 cm have more surface charge density.