Read the following:
(A) The width of central band in diffraction pattern.
(B) The width of first bright band in diffraction pattern.
(C) The width of central band in diffraction pattern if D is doubled
(D) The width of first bright band in diffraction pattern if D is tripled
Choose the correct answer from the options given below in increasing order of width.
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (B), (A), (D), (C)
(A) Width of Central Maximum,
$W_{central}=\frac{2λD}{a}$
(B) Width of first bright fringe,
$W_{bright}=\frac{λD}{a}$
(C) Width of Central Maximum when D is doubled,
$W'_{central}=\frac{4λD}{a}$
(D) Width of first bright fringe when D is tripled,
$W'_{bright}=\frac{3λD}{a}$
$⇒(B)<(A)<(D)<(C)$