The UC Davis physicist measures the thickness of a layer of a benzene withnb= 1.50 by shiningmonochromatic light onto the film and varying the wavelength of the light (the film is in the air withn= 1). She finds that the light of wavelength 635 nm is reflected most strongly from the film. a) What is the minimum thickness of the film?b) What would be the wavelength of the most reflected visible light if the same layer was placed onthe surface of water withnw= 1.3 while the laser still shines from the air.

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".