Why cant conductors be charged by friction?

[ngjingyi]

can some1 clear my doubt?

 

[Andy Resnick]

If I understand your question, the way it was explained to me is that the capacitance of the conductor is so high, it exchanges charges very easily with everything else.

Another way to picture it, when you charge yourself walking across a carpet, you can spark discharge to a metal object but not a wooden one because the transfer of charges onto a low-capacitance object happens slowly.

So trying to rub charges off onto a metal object means the metal object returns those charges back too quickly for any appreciable charge to build up.