One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. Having recently studied optics in your physics class, you're not too surprised to see that the patch of light seems to be a circular diffraction pattern. It appears that the central maximum is about $2$ cm across, and you estimate that the distance from the window shade to the wall is about $3$ m $.$

Part A

Estimate the average wavelength of the sunlight $($in nm $).$

$350$ nm

$450$ nm

$550$ nm

$650$ nm

$750$ nm

Part B

Estimate the diameter of the pinhole $($in mm$).$

Express your answer in millimeters.

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