Kindly refer to the question description.

A  conducting  sphere  having  charge  and  radius  a  is   kept  centrally  inside  a  conducting  shell  having  charge     and  radius  b  ( a  <  b ). 

The  electric  potential  on  the  spherical  shell  of  radius  R  and  on  the  surface  of  the  sphere  of  radius  r  are  respectively

 

 

Hence,the  potential  difference  between  the  surfaces  of  the  two  spheres  is 

 

The  above  equation  shows  that  the  smaller  sphere  is  at  a  higher  potential  as  compared  to  the  large  spherical  shell.  So  if  the  two  are  connected  through  a  conductor,  then  the  electric  charge  will  flow  from  the  smaller  sphere  to  the  larger  spherical  shell.  So  if  charge  is  transferred  continuously  to  the  smaller  sphere  in  some  way,  then  it  will  accumulate  on  the  larger  shell  thereby  increasing  its  electric  potential  to  a  very  large  value.