Why can't we implement the center tapped full wave rectifier without center-tapped transformer

Ahowler monkey is the loudest land animal and, under some circumstances, can be heard up to a distance of 4.6 km. assume the acoustic output of a howler to be uniform in all directions and that the threshold of hearing is 1.0 × 10-12 w/m2. what is the acoustic power emitted by the howler

What describes the particles in a liquid

What do we mean by the event horizon of a black hole?