When white light consisting of wavelengths ranging from 400 nm to 700 nm passes through water \( (\mu = 4/3) \), then the wavelength range in water will be:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 300 nm - 525 nm
When light enters a medium, its frequency stays the same, while its speed and wavelength both fall by the factor \( \mu \).
\( \displaystyle \lambda_{\text{water}} = \frac{\lambda_{\text{air}}}{\mu} \)
\( \displaystyle \frac{400\,\mathrm{nm}}{4/3} = 300\,\mathrm{nm} \qquad \frac{700\,\mathrm{nm}}{4/3} = 525\,\mathrm{nm} \)
So the range in water is 300 nm to 525 nm.