Unknown wavelength λ= 420nm
Given data
Wave length = 700nm
The fifth order overlaps the third order maximum.
The problem can be solved using the idea that since fifth-order maximum exactly overlaps the third-order maximum of the red light . Therefore, the value of for the fifth order maxima is equal to that of third order maxima.
mλ=asinθ
Here, a is the slit-width , m is the order and θ is the angular separation ∴λ1 [tex]m_{1}[/tex]=λ2 [tex]m_{2}[/tex]
[tex]700nm(3)=[/tex]λ2(5)
∴λ2 = [tex]\frac{700(3)}{5}[/tex]
λ2 = 420nm
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