Two wavelengths `lamda_(1)` and `lamda_(2)` are used in Young's double slit expt. `lamda_(1)=430nm`. What is the value of `lamda_(2)` if 4th bright band of one coincides with 6th bright band of the other?

Explanation

We have `beta=(Dlamda)/d` and `beta=("Distance of nth bright band")/("No. of bright bands")=(x("say"))/n`
`:.x/n=(D lamda)/d` i.e. `x=(nD lamda)/d`
Her `(n_(1)Dlamda_(1))/d=(n_(2)Dlamda_(2))/d" ":.n_(1)lamda_(1)=n_(2)lamda_(2)`
`lamda_(2)=(n_(1)lamda_(1))/(n_(2))=(4xx430)/6=286.7nm`