Solutions American physicist who showed that the wavelength of X-rays increased when scattered by electrons has 3 entries with similar clues

• 7-letter words
• dopplerAustrian physicist, d. 1853, famous for his discovery of the effect of movement on perceived wavelengths
• 12-letter words
• thomas-youngEnglish physicist whose major work is concerned with wave theory of light
• 23-letter words
• niels-henrik-david-bohrDanish physicist and pioneer in quantum physics whose theory of the structure of atom incorporated quantum theory for the first time