In a thin film interference, if the film is viewed in white light, which color w

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Question: In a thin film interference, if the film is viewed in white light, which color will be seen at the center of the film? (2022)

Options:

Correct Answer: Red

Exam Year: 2022

Solution:

At the center of a thin film, constructive interference occurs for longer wavelengths (red light), making red the dominant color seen.

In a thin film interference, if the film is viewed in white light, which color will be seen at the center of the film? (2022)

In a thin film interference, if the film is viewed in white light, which color will be seen at the center of the film? (2022)

Step 1: Understand that thin film interference happens when light reflects off the top and bottom surfaces of a thin film.
Step 2: Know that different colors of light have different wavelengths, with red light having a longer wavelength than blue light.
Step 3: Realize that at the center of the film, the path difference between the two reflected light waves is minimal.
Step 4: Remember that constructive interference occurs when the path difference is a multiple of the wavelength.
Step 5: Since longer wavelengths (like red) are more likely to constructively interfere at the center, red light will be the dominant color seen.

Thin Film Interference – The phenomenon where light waves reflected from the top and bottom surfaces of a thin film interfere with each other, leading to constructive or destructive interference depending on the film's thickness and the wavelength of light.
Constructive Interference – Occurs when the path difference between two waves is an integer multiple of the wavelength, resulting in increased amplitude and brightness of the observed color.
Wavelength Dependence – Longer wavelengths (like red light) are more likely to undergo constructive interference in thin films, especially at the center where the film is typically thicker.