Answer
a). $402nm$ , the color is violet
b). $3.45cm$
Work Step by Step
a). Let v be the wavelength.
$nv=dsin\theta$
or, $v=\frac{dsin\theta}{n}=\frac{0.035\times10^{-3}\times sin1.318^{\circ}}{2}=402nm$
Since the wavelength is 402nm, its color is violet.
b). lateral displacement = $y_{n}=\frac{nLv}{d}$
or, $y_{2}=\frac{2\times 1.5\times402\times10^{-9}}{0.035\times10^{-3}}=0.0345m=3.45cm$
