Q. In a Young's double slit experiment, a student observes 8 fringes in a certain segment of screen when a monochromatic light of 600 nn wavelength is used. If the wavelength of light is changed to 400 nm, then the number of fringes he would observe in the same region of the screen is
A) 12
B) 6
C) 8
D) 9
Explanation
[Solution] $n_1\lambda_1 = n_2\lambda_2$: $8 \times 600 = n_2 \times 400$, so $n_2 = 12$. Answer (1).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.