Question

do all objects when rubbed get charged ?why or why not?

Answer 1

No. there are fixed pair of material which on rubbing can produce positive and negative charge.

In the table given below, if an object in the first column is rubbed against the object given in second column, then the object in the first column will acquire positive charge while that in second column will acquire negative charge.

I	II
Woollen cloth	Rubber shoes
Woollen cloth	Amber
Woollen cloth	Plastic object
Fur	Ebonite rod
Glass rod	Silk cloth