Problem $5$: $(25$ points$)$ Take$-$home question: Return to me on Friday $($in class$)$

PART A: A grating that has $3800$ slits per $cm$ produces a second$-$order bright fringe at a $22\mathrm{.}0$ angle. What wavelength of light is being used? $(10$ points$)$

PART B: Select either the farsightedness or nearsightedness defect of the human eye and explain about it$.$ What are its symptoms, one possible reason for it$,$ what is the physics problem in this defect $($the location of the image$),$ and what type of lens would you prescribe to correct the vision in this case? $(2$ points$)$

PART C: Reading glasses of what power is needed for a person whose near point is $125cm,$ so that he can read a computer screen at $55cm($assume a lens$-$eye distance of $1\mathrm{.}8cm$ points$).$ What is basically the defect with eye? $(2$ points$).$ What is the type of the needed lens? $(2$ points$).$ Is the image produced by this lens real or virtual? $(2$ point$).$