Question

Which of the statements are correct with reference to single slit diffraction pattern? (i) Fringes are of unequal width (ii) Fringes are of equal width (iii) Light energy is conserved (iv) Intensities of all bright fringes are equal

• A. (i) and (iii)
• B. (i) and (iv)
• C. (ii) and (iv)
• D. (ii) and (iii)

Answer 1

The Correct Option is A

The topic here is the diffraction pattern formed by a single slit. In a single slit diffraction pattern, we observe a central bright fringe surrounded by dark and bright fringes. Let's evaluate each given statement:

1. Fringes are of unequal width:

   This statement is correct. In a single slit diffraction pattern, the central maximum is the widest and subsequent fringes decrease in width. The widths of the side fringes are not equal as observed in double slit interference patterns. Thus, fringes are of unequal width.

2. Fringes are of equal width:

   This statement is incorrect. As mentioned, the central maximum is broader than the other fringes, which makes the fringes unequal in width.

3. Light energy is conserved:

   This statement is correct. In any optical phenomenon, including diffraction, light energy is conserved according to the principle of the conservation of energy. The energy distribution changes, but the total energy remains constant.

4. Intensities of all bright fringes are equal:

   This statement is incorrect. In a single slit diffraction pattern, the intensity of the bright fringes decreases with increasing order from the center. The central maximum is the most intense, and the intensity decreases for higher order maxima.

Based on the analysis, the correct statements are: (i) Fringes are of unequal width, and (iii) Light energy is conserved. Therefore, the correct answer is (i) and (iii).