Question

A boat has green light of wavelength of $500nm$ 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 $500nm$
• B. Blue of wavelength $376nm$
  
• C. Green of wavelength $376nm$
  
• D. Red of wavelength $665nm$
  

Answer 1

The correct option is C Green of wavelength $376nm$

Wavelength of light on the mast ${\lambda }_m=500nm$

Refractive index of water $n_w=4/3$

Wavelength of light as seen by the diver ${\lambda }_d=\frac{{\lambda }_m}{n_w}$

$\therefore$ ${\lambda }_d=\frac{500}{4/3}$

$⟹$ ${\lambda }_d=376nm$

As frequency of light does not change in the refraction phenomenon.

Thus the green light is observed by the diver.