Question

Thickness of the filmThe UC Davis physicist measures the thickness of a layer of a benzene with nb= 1.50 by shiningmonochromatic light onto the film and varying the wavelength of the light (the film is in the air with n= 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.

Answer 1

Answer:

Explanation:

• Given λ = wavelength of light reflected = 635 nm

• Using the equation ; 2 nb t = (m - (1/2)λ

• nb= 1.50

Plugging the values in the equation ;

• 2 (1.50) t = (1 - (1/2) (635)

• t = 105.83 nm = the minimum thickness of the film

b) To calculate the wavelength of the most reflected visible light ;

• From the equation 2 nb t = mλ

• λ' =  2 nb t/m

Plugging the values into the equation

• 2 (1.50) (105.83) = λ'

• λ' = wavelength = 317.5 nm