Heinrich Rudolph Hertz laid the foundation for the future development of radio, telephone and telegraph. The SI unit of ______ was named as 'hertz' in his honour.

frequency

The correct answer is option 1. frequency.

Heinrich Rudolph Hertz was a German physicist who made significant contributions to the study of electromagnetism. One of his most famous achievements was the experimental proof of the existence of electromagnetic waves, a key development in the understanding of electricity and magnetism.

In 1887, Hertz conducted a series of experiments that demonstrated the existence of electromagnetic waves predicted by James Clerk Maxwell's theory of electromagnetism. He generated and detected these waves in the laboratory, confirming their properties such as reflection, refraction, diffraction, and polarization. These experiments not only verified Maxwell's theory but also laid the groundwork for the development of wireless communication technologies.

In recognition of Hertz's pioneering work in the field of electromagnetism and his experimental confirmation of electromagnetic waves, the unit of frequency in the International System of Units (SI) was named the "hertz" (symbol: Hz) in his honor. One hertz corresponds to one cycle per second of a periodic phenomenon, such as the oscillation of an electromagnetic wave.

Therefore, when we measure frequency, such as the frequency of radio waves, sound waves, or any other periodic phenomenon, we use the unit "hertz" as a tribute to Heinrich Rudolph Hertz's groundbreaking contributions to the understanding of electromagnetic radiation and its applications in communication technology.