hertz [for Heinrich R. Hertz], abbr. Hz, unit of frequency, equal to 1 cycle per second. The term is combined with metric prefixes to denote multiple units such as the kilohertz (1,000 Hz), megahertz (1,000,000 Hz), and gigahertz (1,000,000,000 Hz).

Hertz, Heinrich Rudolf, 1857-94, German physicist. He confirmed J. C. Maxwell's electromagnetic theory and in the course of experiments (1886-89) produced and studied electromagnetic waves (known also as hertzian waves, or radio waves). He demonstrated that these are long, transverse waves that travel at the velocity of light and can be reflected, refracted, and polarized like light. Hertz also investigated electric discharge in rarefied gases. The unit of frequency called hertz was named in his honor. His writings include Electric Waves (1890, tr. 1893) and Principles of Mechanics (1894, tr. 1899).

Hertz, Gustav, 1887-1975, German physicist. He is noted for his work on the atom, and he shared with James Franck the 1925 Nobel Prize in Physics for research (1914) on the effects of the impact of electrons on atoms. In 1928 he became professor at the Technical Institute, Berlin, but resigned in 1934 in protest against Nazi policies and went to work for Siemens. He worked on atomic bomb research for the USSR from 1945 to 1954, when he returned to Germany to teach at Karl Marx Univ. in Leipzig.

(born Feb. 22, 1857, Hamburg, Ger.—died Jan. 1, 1894, Bonn) German physicist. While a professor at Karlsruhe Polytechnic (1885–89), he produced electromagnetic waves in the laboratory and measured their length and velocity. He showed that the nature of their vibration and their susceptibility to reflection and refraction were the same as those of light waves, and he proved that light and heat are electromagnetic radiations. He was the first to broadcast and receive radio waves. In 1889 he was appointed professor at the University of Bonn, where he continued his research on the discharge of electricity in rarefied gases. The hertz (Hz), a unit of frequency in cycles per second, is named for him.

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(born Feb. 22, 1857, Hamburg, Ger.—died Jan. 1, 1894, Bonn) German physicist. While a professor at Karlsruhe Polytechnic (1885–89), he produced electromagnetic waves in the laboratory and measured their length and velocity. He showed that the nature of their vibration and their susceptibility to reflection and refraction were the same as those of light waves, and he proved that light and heat are electromagnetic radiations. He was the first to broadcast and receive radio waves. In 1889 he was appointed professor at the University of Bonn, where he continued his research on the discharge of electricity in rarefied gases. The hertz (Hz), a unit of frequency in cycles per second, is named for him.

Learn more about Hertz, Heinrich (Rudolf) with a free trial on Britannica.com.