Answer
(a) This is the pattern produced by a single slit.
(b) $a = 1.55\times 10^{-4}~m$
Work Step by Step
(a) The pattern shows a wide and bright central maximum with narrow low intensity bands on either side. This is the pattern produced by a single slit.
(b) We can find the width of the single slit aperture:
$w = \frac{2~\lambda~L}{a}$
$a = \frac{2~\lambda~L}{w}$
$a = \frac{(2)(620\times 10^{-9}~m)(2.5~m)}{2.0\times 10^{-2}~m}$
$a = 1.55\times 10^{-4}~m$
