1) In Young's double-slit experimental setup if the wavelength alone is doubled, the bandwidth β becomes A) $\frac{\beta}{2}$ B) $2\beta$ C) $3\beta$ D) $\beta$ Answer: Option BExplanation:Fringe width, $\beta= \frac{\lambda D}{d}$ When λ alone is doubled then fringe width becomes $\beta '= \frac{\left(2\lambda\right) D}{d}$ = 2β
