Q 12-10-155NEETNEET 2022Top questionEasy
In a Young's double slit experiment, a student observes $8$ fringes in a certain segment of screen when a monochromatic light of $600$ nm 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
Answer: (A) $12$
Fringe width $\beta = \dfrac{\lambda D}{d} \propto \lambda$. For a fixed length of screen, $n\beta$ is constant, so $n_1\lambda_1 = n_2\lambda_2$.
$$n_2 = \frac{8 \times 600}{400} = 12$$
Solution by Sreeraj P, M.Sc Physics