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Light Waves — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsLight Waves1 Mark
Question
When light is refracted into a medium:
  1. Its wavelength and frequency both increase
  2. Its wavelength increases but frequency remains unchanged
  3. Its wavelength decreases but frequency remains unchanged.
  4. Its wavelength and frequency both decrease.
✓

Answer

  1. Its wavelength decreases but frequency remains unchanged.
Explanation:
Frequency of a light wave, as it travels from one medium to another, always remains unchanged, while wavelength decreases.
Decrease in the wavelength of light entering a medium of refractive index $\mu$, is given by,
$\lambda_\text{M}=\frac{\lambda}{\mu},$
Where $\lambda_\text{M}$ = wavelength in medium
$\lambda$ = wavelength in vacuum
$\mu$ = refractive index

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