In a thin film interference, which of the following conditions leads to a dark f

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Question: In a thin film interference, which of the following conditions leads to a dark fringe?

Options:

Correct Answer: Path difference is an odd multiple of lambda

Solution:

A dark fringe occurs when the path difference is an odd multiple of the wavelength (λ/2), leading to destructive interference.

In a thin film interference, which of the following conditions leads to a dark fringe?

In a thin film interference, which of the following conditions leads to a dark fringe?

Correct Answer: Path difference is an odd multiple of λ/2

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 when light waves meet, they can either add together (constructive interference) or cancel each other out (destructive interference).
Step 3: Recognize that a dark fringe appears when the light waves cancel each other out.
Step 4: Learn that this cancellation happens when the path difference between the two waves is an odd multiple of half the wavelength (λ/2).
Step 5: Conclude that for a dark fringe, the condition is that the path difference = (2n + 1)(λ/2), where n is an integer (0, 1, 2, ...).

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.
Path Difference – The difference in distance traveled by two waves; for dark fringes, this difference must be an odd multiple of half the wavelength.
Destructive Interference – Occurs when two waves combine in such a way that their amplitudes cancel each other out, resulting in a lower intensity or dark fringe.