Question

The number of peaks of the interference formed if the slit width is doubled while keeping the distance between the slits same will be:

• A. 1
• B. 2
• C. 3
• D. 4

Hint:

When the width of the slit is increased, the diffraction effects become more pronounced, reducing the width of the central maximum and the effective space for interference fringes within it.

Answer 1

The Correct Option is C

When the slit width is doubled, the diffraction envelope becomes narrower because the angular position of the first diffraction minimum is inversely proportional to the slit width. The number of interference fringes within the central diffraction peak will remain the same because the fringe separation is determined by the distance between the slits, not the slit width. Hence, the number of peaks of interference fringes within the central diffraction peak is 3. Thus, the number of peaks of interference is 3.