Answer
(a) This is the pattern produced by a double slit.
(b) $d = 1.55\times 10^{-4}~m$
Work Step by Step
(a) The pattern shows the bright bands to be of equal width and decreasing gradually in intensity from a central maximum. This is the pattern produced by a double slit.
(b) We can find the spacing between the slits:
$y = \frac{\lambda~L}{d}$
$d = \frac{\lambda~L}{y}$
$d = \frac{(620\times 10^{-9}~m)(2.5~m)}{1.0\times 10^{-2}~m}$
$d = 1.55\times 10^{-4}~m$
