Answer:
225nm
Explanation:
The Maxima of diffraction girating
dsin( θ)= m(λ)
Where θ)= angle between central axis and corresponding point
The wavelength is to corresponding sin( θ)
Then the maximum number of (λ) can be seen by setting sin( θ)= 1 then
d= m(λ)
At fifth order maximum m=1 then
d= 5(λ)
Where d= distance between the slit and with girating of 1/890rullig/mm
d= 1/890rullig/mm= 8.90×10^-6m
At maximum wavelength
d= 5(λ)
(λ)=5/d
= 8.90×10^-6m/5
=2.75*10^-7
= 275nm
Therefore, longest wavelength that forms an intensity maximum in the fifth order is 275nm
