What nineteenth-century invention led to the expanded use of hydroelectric power?

TURBINES

Explanation:

The invention of turbines in the 19th century brought about significant changes in the field of technology. These turbines were initially used in wind mills in order to generate electricity. They are also used in the dams now for the same purpose. The working principle of turbines in a windmill is very simple. The wind turbines are comprised of two or three propeller like blades and a rotor. The wind energy forces these blades to rotate around a rotor which is further connected to a main shaft. This main shaft then spins a generator in order to produce electricity.

Thus, the use of turbines in the 19th century led to the expanded use of hydroelectric power.