Question

The condition for constructive 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

The correct option is B Integral multiple of wavelength

Constructive interference at a point between the two waves takes place if the path difference between the waves at that point is equal to integral multiple of wavelength of the waves.
So, path difference $\Delta x=n\lambda$
where $n$ must be an integer.