In Young's double slit experiment, the 7th maximum with wavelength $λ_1$ is at a distance $d_1$ and that with wavelength $λ_2$ is at a distance $d_2$. Then $d_1/d_2$ is

$λ_1/λ_2$ $λ_2/λ_1$ $λ_1^2/λ_2^2$ $λ_2^2/λ_1^2$

$λ_1/λ_2$

$7β_1=d_1=7\frac{λ_1D}{2d}$ and $7β_2=d_2=7\frac{λ_2D}{2d}$ $∴\frac{d_1}{d_2}=\frac{λ_1}{λ_2}$