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Stage 1 of 2
Hertz
German · 1880s
"Hertz (a surname)"
the surname of the physicist Heinrich Hertz, who proved the existence of electromagnetic waves at Karlsruhe in 1887
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Stage 2 of 2
hertz
English · 1930
"unit of frequency"
adopted as the unit of frequency by the International Electrotechnical Commission in 1930
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