In a double-slit experiment to determine an unknown wavelength
of light, the measured total distance between 16 maxima (8 on each
side of the central maximum) is 16.8 cm. The screen is located 3.45
m from the double slits, whose centers are 0.21 mm apart.
(a) What is the wavelength of the light?
(b) Suppose white light was sent through the same apparatus.
What would be the width of the n = 1 rainbow projected on the
screen? Hint: the visible spectrum runs continuously from about 400
nm to 700 nm.