Why is electrical power required at all when the elevatore is descending ? Why should there be a limit on the number of passengers in this case ?

Why is electrical power required at all when the elevator is descending? Why should there be a limit on the number of passengers in this case?

Why is electrical power required at all when the elevator is descending ? Why should there be a limit on the number of passengers in this case ?

Why is an electric fuse required in all electrical appliances?

Why should we breathe all the time ?

Why is chemical signal required along with electrical impulses in higher animals ?

Answer the following : Explain the generation of sound in a loudspeaker with the help of neat diagram. Why should there be limit on the loudness of loudspeaker?

Vivipary automatically limits the number of offspring in a litter. Why?