Answer:
Option *
Explanation:
In a biprism experiment, wavelength of the light is given as
$\lambda=\frac{d\beta}{D}$ .......(i)
where, $\beta$ is the fringe width,
d is the distance between the two sources and D is the distance between the source and eyepeice.
Given , D=1.2 m
d= 0.84 mm=0.84 x 10-3 m and
$\beta=\frac{2.799\times 10^{-2}}{30}=9.33 \times 10^{-4}$
Substituting these values in Eq.(i) , we get
$\lambda=\frac{0.84 \times 10^{-3}\times9.33 \times 10^{-4}}{1.2}=6.531 \times 10^{-7}m =$
=6531 Å
