In a thin film interference, if the film is of thickness t and the wavelength of
Practice Questions
Q1
In a thin film interference, if the film is of thickness t and the wavelength of light is λ, what is the condition for destructive interference?
2t = (m + 1/2)λ
2t = mλ
t = mλ
t = (m + 1/2)λ
Questions & Step-by-Step Solutions
In a thin film interference, if the film is of thickness t and the wavelength of light is λ, what is the condition for destructive interference?
Step 1: Understand that thin film interference happens when light waves reflect off the top and bottom surfaces of a thin film.
Step 2: Know that for destructive interference, the waves need to cancel each other out.
Step 3: Realize that when light reflects off a surface, it can undergo a phase change. For a film with a higher refractive index, the wave reflecting off the top surface undergoes a phase change of 180 degrees (or half a wavelength).
Step 4: For destructive interference, the path difference between the two waves must equal an odd multiple of half the wavelength. This means the waves are out of phase.
Step 5: The condition for destructive interference can be expressed mathematically as 2t = (m + 1/2)λ, where m is an integer (0, 1, 2, ...).
