atoms of element a decay to atoms of element b with a half life of 20000 years. if there are 10000 atoms of a to begin with (and 0 atoms of b) how long will it take for there to be 2500 atoms of a

Imagine that the rightward current flows in the rod for a short time. as a result, what will the net charge on the right and left ends of the rod become? left end negative and right end positive left end negative and right end negative left end negative and right end nearly neutral left end nearly neutral and right end positive both ends nearly neutral