What is the minimum thickness of a soap bubble for which the first order of cons
Practice Questions
Q1
What is the minimum thickness of a soap bubble for which the first order of constructive interference occurs for light of wavelength λ? (2019)
λ/4
λ/2
λ
3λ/4
Questions & Step-by-Step Solutions
What is the minimum thickness of a soap bubble for which the first order of constructive interference occurs for light of wavelength λ? (2019)
Step 1: Understand that a soap bubble has two surfaces: the outer surface and the inner surface.
Step 2: When light hits the soap bubble, some light reflects off the outer surface and some reflects off the inner surface.
Step 3: Recognize that when light reflects off a medium with a higher refractive index (like soap), it undergoes a phase change of 180 degrees (or half a wavelength).
Step 4: For constructive interference to occur, the path difference between the two reflected light waves must be a whole number of wavelengths (nλ).
Step 5: The minimum thickness of the soap bubble for the first order of constructive interference is when the path difference is equal to one wavelength divided by 2, due to the phase change from the reflection.
Step 6: Therefore, the minimum thickness (t) for the first order of constructive interference is t = λ/4.