A slit has a width of w1 = 4.0 × 10-6 m. when light with a wavelength of λ1 = 648 nm passes through this slit, the width of the central bright fringe on a flat observation screen has a certain value

A slit has a width of w1 = 4.0 × 10-6 m. when light with a wavelength of λ1 = 648 nm passes through this slit, the width of the central bright fringe on a flat observation screen has a certain value. with the screen kept in the same place, this slit is replaced with a second slit (width w2), and a wavelength of λ2 = 671 nm is used. the width of the central bright fringe on the screen is observed to be unchanged. find w2.