Solved: PHYSICS Question for NEET

NEET PHYSICSEasy

In Young's double slit experiment, if the wavelength of light used is increased (say from violet to red) then the:

fringe width decreases.

fringe width increases.

central bright fringe becomes dark.

fringe width remains unaltered.

Formula: The fringe width ( $\beta$ ) in Young's Double Slit Experiment is given by the formula: $\beta = \frac{\lambda D}{d}$ where $\lambda$ is the wavelength of light, $D$ is the distance of the screen from the slits, and $d$ is the distance between the slits.
Analysis: The formula shows that fringe width is directly proportional to the wavelength ( $\beta \propto \lambda$ ).
Application: Red light has a longer wavelength than violet light ( $\lambda_{red} > \lambda_{violet}$ ). Therefore, if the light source is changed from violet to red (increasing $\lambda$ ), the fringe width $\beta$ will increase.
Conclusion: The fringe width increases.

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