Question

A point source of white light is being viewed normally through a thin prism of refracting angle $3^o$ having refractive index 1.49 and 1.51 for violet and red light respectively and source is placed $6\pi$ cm away from the prism. Find the distance between the red and violet images formed due to refraction by prism (Take : ${\pi }^2=10$)

• A. 0.01 mm
• B. 0.014 mm
• C. 0.016 cm
• D. 0.018 cm
• E. 0.02 cm

Answer 1

Answer: (E)

0.02 cm

Deviation of a particular wavelength on passing through a prism of refracting angle $A=A(\mu -1)$

Hence angle of seperation between red and violet light $=A({\mu }_{red}-{\mu }_{violet})=(3\times \frac{\pi }{180})0.02$ radians

Thus the separation between the two light on travelling $6\pi$ cm

becomes $6\pi \times (3\times \frac{\pi }{180})0.02$ cm=$0.02$cm