Consider two statements given below :

Statement-I: In YDSE, if distance between slits & screen increases, fringe width also increases. Statement-II: If wavelength of light used in YDSE increases, fringe width also increases. Which of the following options is correct?

The correct option is: Both statements I & II are correct

Explanation:

In Young's Double Slit Experiment (YDSE), the formula for fringe width ($\beta$) is given by:

$\beta =\frac{\lambda D}{d}$

where:
• $\lambda$ is the wavelength of the light used,
• $D$ is the distance between the slits and the screen, and
• $d$ is the distance between the two slits.

Let us analyze both statements based on this relationship:

Analysis of Statement-I:
From the formula, fringe width $\beta$ is directly proportional to the distance between the slits and the screen ($D$), i.e., $\beta \propto D$.
Therefore, if the distance between the slits and screen increases ($D$ increases), the fringe width ($\beta$) also increases.
Hence, Statement-I is correct.

Analysis of Statement-II:
From the formula, fringe width $\beta$ is also directly proportional to the wavelength of the light used ($\lambda$), i.e., $\beta \propto \lambda$.
Therefore, if the wavelength of light used increases ($\lambda$ increases), the fringe width ($\beta$) also increases.
Hence, Statement-II is correct.

Since both Statement-I and Statement-II are correct, the correct choice is Both statements I & II are correct.