Apool of water is covered with a film of oil which is 234 nm thick. for what wavelength of visible light (in air) will the reflected light constructively interfere? the index of refraction of the oil is 1.65. visible light (in air) has wavelengths between 430 nm (blue) and 770 nm (red) in air. assume that the incident light is normal to the surface of the oil.

Answer

given,

thickness of the oil film = 234 n m

refractive index of oil = n = 1.65

Visible light (in air) has wavelengths between 430 nm (blue) and 770 nm (red)

λ = ?

condition of constructive interference

2 n t + λ/2 = k λ

now,

at k = 1

not between the visible range

at k =2

above wavelength is in the visible range.

d₁ = displacement of tern from arctic to antarctic = 11000 miles

d₂ = displacement of tern from antarctic to arctic =   - 11000 miles

d = total displacement for the journey

total displacement for the journey is given as

d = d₁ + d₂

d = 11000 + (-11000)

d = 0 miles

t₁ = time of travel from arctic to antarctic = 3 months = 3 x 30 days = 90 days

t₂ = time of travel from antarctic to arctic = 3 months = 3 x 30 days = 90 days

t = total time of travel

total time of travel is given as

t = t₁ + t₂

t = 90 + 90

t = 180 days

average velocity is given as

average velocity = total displacement/ total time

v = d/t

v = 0/180

v = 0 miles/day