Question

Young's double-slit experiment is carried out by using green, red and blue light using one colour at a time. The fringe widths recorded are $\beta _{G}$ , $\beta _{R}$ and $\beta _{B}$ respectively. Then,

• A. $\beta _{\text{G}} > \beta _{\text{B}} > \beta _{\text{R}}$
• B. $\beta _{\text{B}} > \beta _{\text{G}} > \beta _{\text{R}}$
• C. $\beta _{\text{R}} > \beta _{\text{B}} > \beta _{\text{G}}$
• D. $\beta _{\text{R}} > \beta _{\text{G}} > \beta _{\text{B}}$

Answer 1

Answer: (D)

We know that fringe width is given by
$\beta =\frac{\lambda D}{d}$
$\because $ $\lambda _{\text{R}}>\lambda _{\text{G}}>\lambda _{\text{B}}$
$\therefore \beta _{\text{R}}>\beta _{\text{G}}>\beta _{\text{B}}$