To reduce light-induced degradation of delicate seventeenth-century oil paintings, curators at the Vane Gallery replaced all traditional halogen spotlights with light-emitting diode (LED) fixtures that emit zero ultraviolet radiation. Because ultraviolet rays were previously identified as a chief contributor to varnish oxidation, the curators concluded that overall pigment and varnish breakdown in the gallery's collection will decrease by at least 40 percent over the coming decade. Which of the following statements, if true, most seriously weakens the curators' argument?
- AThe financial savings resulting from lower energy consumption after switching to LED lighting will enable the gallery to expand its collection of seventeenth-century artwork.
- The specific spectrum of high-energy visible blue light emitted by the new LED fixtures triggers chemical oxidation in seventeenth-century pigments at rates comparable to ultraviolet radiation.Cevap
- CControlled laboratory trials indicated that traditional halogen spotlights cause significantly more rapid varnish yellowing than any other conventional incandescent light source.
- DEnvironmental humidity fluctuations in art galleries generally present a greater long-term risk to wooden structural supports than light exposure does.
- EVisitors to the gallery report that paintings illuminated by LED fixtures display greater visual clarity than those previously lit by halogen lamps.
Cevap
The argument is most seriously weakened by the statement that high-energy visible blue light emitted by the new LED fixtures triggers chemical oxidation in seventeenth-century pigments at rates comparable to ultraviolet radiation.
The argument concludes that switching from halogen to LED lighting will decrease overall painting degradation by at least 40 percent because LEDs emit no UV radiation. The correct answer points out that the new LED lights emit high-energy visible blue light that causes chemical oxidation at rates comparable to UV light. By showing that the new lighting system introduces a different wavelength of light that causes equivalent damage, it demonstrates that the expected reduction in overall degradation is unlikely to occur.
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Weakening Causal and Plan-Goal Arguments by Identifying Side Effects or Alternative Causes
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