We need more evidence to be provided
        
             
        
        
        
A direct-current (DC) generator is a rotating machine that supplies an electrical output with unidirectional voltage and current. ... The field is produced by direct current in field coils or by permanent magnets on the stator. The output, or armature, windings are placed in slots in the cylindrical iron rotor.
        
             
        
        
        
4A. PE = MxGxH. (You can consider g as 9.8 / 10m/s as well)
 509 J = 12x10xH
 
 509 J = 120xH
 
 H = 509/120 
 
 H = 4.24 m
Hope u got the answer....pls rate the answer if it is helpful for u....and I'm sorry I could not understand B part so I didn't do it.
Thank you