Question

A boat has green light of wavelength $\lambda$ = $500\, nm$ on the $MAST$. What wavelength would be measured and what colour would be observed for this light as seen by a diver submerged in water by the side of the boat?
Given $n _W= 4/3$

• A. Green of wavelength $500 \,nm$
• B. Blue of wavelength $376\, nm$
• C. Green of wavelength $375 \,nm$
• D. Red of wavelength $665\, nm$

Answer 1

Answer: (B)

When light travels from rarer to denser medium its wavelength reduces. Wavelength in
water $=\frac{\lambda_{a}}{\mu_{w}}$
$=\frac{500}{(4 / 3)}=375 nm \approx 376 nm \text { (Blue colour) }$