Light reflected from air film between glass plates

[domyy]

Homework Statement

Hi

Light of 500nm wavelength is reflected from a thin film of air between two glass plates. The thickness of the film is 1000mn.

a) How much farther does the light reflected from bottom surface travels than the light reflected from the top of the film (assuming normal incidence)?

b) How many wavelength of light does this represent?

Homework Equations

λ ≈ 2d

The Attempt at a Solution

For a)

λ = 2(1000nm) = 2000nm

For b)

2000nm/500nm = 4

Is it correct?

 

[collinsmark]

Homework Statement

Hi

Light of 500nm wavelength is reflected from a thin film of air between two glass plates. The thickness of the film is 1000mn.

a) How much farther does the light reflected from bottom surface travels than the light reflected from the top of the film (assuming normal incidence)?

b) How many wavelength of light does this represent?

Homework Equations

λ ≈ 2d

The Attempt at a Solution

For a)

λ = 2(1000nm) = 2000nm

For b)

2000nm/500nm = 4

Is it correct?

It looks correct to me.

The variable λ is conventionally reserved for the wavelength of the light involved (not necessarily the extra distance traveled). So your use of 'λ' is a somewhat unconventional. However, your numerical answers look correct to me.