Ultraviolet (UV) light was discovered in 1801 by Johann Ritter through an experiment involving photographic paper and light beyond the violet end of the visible spectrum.
Johann Ritter's Experiment: Unveiling the Invisible
Johann Ritter's discovery of UV light was a pivotal moment in understanding the electromagnetic spectrum. His experiment was based on the following principles:
- Background: Ritter knew that photographic paper darkened more quickly when exposed to blue light compared to red light.
- Hypothesis: He hypothesized that there might be energy beyond the visible violet end of the spectrum that could also affect the photographic paper.
- Experiment: Ritter exposed photographic paper to light just beyond the violet end of the visible spectrum.
- Observation: He observed that the paper darkened even faster than when exposed to violet light.
Key Findings and Conclusion:
This experiment demonstrated that there was indeed a form of invisible light beyond violet, which Ritter initially referred to as "chemical rays" because of its ability to cause chemical reactions (like darkening photographic paper). This invisible light is what we now know as ultraviolet (UV) radiation.
In summary, Johann Ritter discovered UV light by observing its effect on photographic paper beyond the visible violet spectrum, confirming the existence of electromagnetic radiation beyond what the human eye can perceive.
