C. V. Raman Asks About Blue Water
Written by Studio AM.
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In 1921, Indian physicist Chandrasekhara Venkata Raman sailed across the Mediterranean Sea. Its intense blue color held his attention. A common explanation emphasized reflected sky light, but Raman suspected that the water itself scattered sunlight in important ways. He returned to India with a question that could be tested.
Raman and his collaborators directed light through transparent materials and examined the scattered light with spectroscopes. Most scattered light kept its original wavelength. A very small portion changed wavelength after exchanging energy with molecules in the material. The shifted lines were faint, so the experiments required filtered light, careful observation, and repeated checks.
In 1928, Raman and K. S. Krishnan reported clear evidence of this effect. It provided a new way to study molecular structure: the pattern of shifted light could act like a material signature. Laboratories soon confirmed the finding. Raman received the 1930 Nobel Prize in Physics for work on the scattering of light and the effect named for him. Before the sea voyage, Raman had already studied sound and light. His research community and practical instruments gave him ways to investigate the new question. Curiosity supplied direction; disciplined measurement turned it into public evidence.
Modern Raman spectroscopy is used to identify substances in fields from chemistry to art conservation. Its usefulness rests on a minute difference in scattered light. Raman's achievement shows how a broad question (why does this look blue?) can be narrowed into measurements precise enough to reveal how light and matter exchange energy.
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Questions
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Question 1 of 4
What is the main idea of the biography?
The answer is B: Raman turned a question about scattered light into careful evidence for a molecular effect with lasting scientific uses.
The biography connects curiosity, experimental discipline, the wavelength shift, and later scientific value.
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Question 2 of 4
Why could the shifted-light pattern identify a material?
The answer is C: Different molecules interact with light in characteristic ways that produce a signature pattern.
Calling the pattern a material signature implies that molecular interactions create distinguishable results.
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Question 3 of 4
What does “minute” mean in the final paragraph?
The answer is D: extremely small
The passage repeatedly describes the changed portion and its lines as very small and faint.
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Question 4 of 4
In what year did Raman and Krishnan report clear evidence of the effect?
The answer is A: 1928
The third paragraph dates their report of clear evidence to 1928.
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