$(3$ pts$)$ A laser beam passes through a $0\mathrm{.}0500-mm$ slit, and the resulting diffraction pattern is viewed on a screen $2\mathrm{.}20$ m from the slit. The distance between adjacent $n=1$ and $n=2$ dark fringes is $20\mathrm{.}0$ mm $.$ The screen is far enough away, and the fringes close enough together to justify the small$-$angle approximation. What is the wavelength of the laser light?

A$.633\mathrm{.}5$ nm

B$.532\mathrm{.}5$ nm

C$.454\mathrm{.}5$ nm

D$.400\mathrm{.}5$ nm

$(3$ pts$)$ A non$-$viscous fluid flows through a pipe with laminar flow. The pipe has vertical and horizontal wide sections that are connected by a narrow section, as shown. Consider points $1$ and $2,$ which are at the same height, and point $3$ which is lower than the other two points. Note you do not know the crosssectional areas of the pipes, or the height of point $3$ relative to the other points, but you know that the widths of the wide sections are the same. Which of the following statements about the pressure at the three points indicated are correct?

i$.,P_1>P_2$

ii$.,P_1>P_3$

iii. $,P_2$

$A.i.$ only

$B.ii.$ only

$C.i.$ and $ii.$

$D.i.$ and iii.

$E.$ All $of$ these statements are correct.