ISRO Electrical Engineering (EE) 2023 - Question 64

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Wavelength of which material is considered for defining the standard metre

  • A. Helium
  • B. Xenon
  • C. Neon
  • D. Krypton

Answer: D. Krypton

Explanation: The standard metre was defined in 1960 based on 1,650,763.73 wavelengths of orange-red light emitted by Krypton-86.

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