Question

why parallwl combination is use i sted of series combination

Answer 1

because in series combination potential diff divide
because if one application would damaged then all aplicacion do not work
because constant current reach everywhere which is very dangerous for small equipment

Answer 2

parallel combination is generally used because series combination needs the circuit to be complete from one end to other end.....and if by chance one circuit is broken the whole series will be stop....
hence parallel combination is used because it allows to join several other circuits.
also series combination takes more voltage and sometimes it leads to loss of electricity...

hope it helps u dear!

regards
Mohit Khairnar