Hertz's Spark
Plate 018 Physics Poster
Plate 18 speaks for itself: “Light, without the light.”
The Physics
Hertz made sparks in one circuit and detected sparks in a separate loop across the room, showing that electromagnetic waves exist and travel like light, as Maxwell predicted.
c = 1 / √(μ₀ ε₀)
- c: speed of light in vacuum, m s⁻¹
- μ₀: vacuum permeability, N A⁻²
- ε₀: vacuum permittivity, F m⁻¹
c = 299 792 458 m/s (exact). Karlsruhe, 1886–88.
Sources
- H. Hertz, Ann. Phys. 270, 551 (1888).
- SI Brochure, 9th ed. (2019): exact c.
On the poster
Plate 018, “Hertz's Spark”: the pixel-art plate with its slogan “Light, without the light.”, the key equation and the facts panel shown above. Pixelated Physics. Physics. Personified.
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