The third paragraph's second phrase says that building hydroelectric power facilities "costs a considerable deal of money."
The final phrase of the opening paragraph states this.
A closed loop between the generator and the motor is only created by switch number three. While shutting 1 has no effect, closing 2 results in a short circuit.
Every point on the belt is moving at the same linear speed, and as a result, so are all the points outside of each pulley. The pulley with the shortest circumference will thus spin the most quickly.
This detail is provided in the final clause of the first paragraph.
The penultimate language of the second paragraph, which reads, "Hydroelectric plants are regarded to be one of the most durable systems, which means that they keep their efficiency throughout their lifespan," implies this.
This statement suggests that hydroelectric power plants are discovered to have a number of better attributes when compared to other power plants.