P4 D. [4 pts] Light of wavelength ( 630 mathrm{~nm} ) falis perpendicularly on a soap firm ( (n=1,33) ) suspended in air. What are the (a) least and (c) eecond least thichonesses of the fim for which the refiections from the firm undergo fully destructive intarterence?

P4 i. [4 pts] Light of wavelength 630nm falis perpendicularty on a soap fim (n=1,33) suspended in air. What are the (a) least and (b) second least thicknesses of the fim for which the reflections from the firm undergo fully destructive interterence