# Light of 500nm wavelength is reflected

#### domyy

1. 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?

2. Homework Equations

λ ≈ 2d

3. The Attempt at a Solution

For a)

λ = 2(1000nm) = 2000nm

For b)

2000nm/500nm = 4

Is it correct? 1. Homework Statement

2. Homework Equations

3. The Attempt at a Solution

Related Introductory Physics Homework Help News on Phys.org

#### collinsmark

Homework Helper
Gold Member
1. 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?

2. Homework Equations

λ ≈ 2d

3. 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.