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

Step 1: Analyze Fringe Width

Single slit diffraction fringes are unequal in width. Central bright fringe is widest.

Step 2: Analyze Fringe Width (Statement (i) vs (ii))

(i) Fringes are of unequal width - Correct
(ii) Fringes are of equal width - Incorrect

Step 3: Analyze Energy Conservation

Diffraction is redistribution of energy. Energy is conserved.

Step 4: Analyze Energy Conservation (Statement (iii))

(iii) Light energy is conserved - Correct

Step 5: Analyze Bright Fringe Intensities

Intensities of bright fringes are not equal. Central fringe is most intense; intensity decreases for outer fringes.

Step 6: Analyze Bright Fringe Intensities (Statement (iv))

(iv) Intensities of all bright fringes are equal - Incorrect

Step 7: Identify Correct Statements

Correct statements are (i) and (iii).

Step 8: Match to Option

Option (A) is (i) and (iii).

Final Answer: The final answer is $(i) \text{ and } (iii)$

Answer 2

(i) Fringes are of unequal width: This statement is incorrect. In single slit diffraction, the fringes are not of unequal width. The central maximum is wider than the secondary maxima, but the overall structure of the fringes involves equal angular width for all diffraction fringes. 

(ii) Fringes are of equal width: This statement is correct. The angular width of all the diffraction fringes (except the central one) is the same, though the intensity of the fringes changes. 

(iii) Light energy is conserved: This statement is correct. The total energy in the diffraction pattern is the same as the energy incident on the slit. The energy is redistributed, but the total energy is conserved. 

(iv) Intensities of all bright fringes are equal: This statement is incorrect. In a single slit diffraction pattern, the intensity of the bright fringes decreases as we move away from the central maximum.