- 0.2
- 1.2
- 0.8
- 1.5
Solution: 0.8
$ We\text{ }know\text{ }that~ $
$ Distance\text{ }of\text{ }the~nth~bright\text{ }fringe~is\,given\,by: $
$ {{y}_{n}}=\frac{n\lambda D}{d} $
$ \Rightarrow {{y}_{n}}\propto \lambda $
$ \therefore \frac{{{X}_{blue}}}{{{X}_{green}}}=\frac{{{\lambda }_{1}}}{{{\lambda }_{2}}} $
$ \frac{{{X}_{blue}}}{{{X}_{green}}}=\frac{4350}{5450} $
$ \frac{{{X}_{blue}}}{{{X}_{green}}}=0.8 $