Question

The condition for destructive interference is path difference should be equal to :

• A. Odd integral multiple of wavelength
• B. Integral multiple of wavelength
• C. Odd integral multiple of half wavelength
• D. Integral multiple of half wavelength

Answer 1

Answer: (C)

Odd integral multiple of half wavelength

Destructive interference at a point between the two waves takes place if the path difference between the waves at that point is equal to odd integral multiple of half wavelength of the wave.
So, path difference $\Delta x=(n+\frac{1}{2})\lambda$
where $n$ must be an integer.