The line-width of a bright fringe is sometimes defined as the separation between the points on the two sides of the central line where the intensity falls to half the maximum. Find the line-width of a bright fringe in a Young's double slit experiment in terms of `lamda`, d and D where the symbols have their usual meanings

Answer

A, B, D

Explanation

The line width of a bright fringe is sometimes defined as the separation between the point on the two sides of the central line where the intensity falls to half the maximum.
`y=+-(Dlamda)/(4d)`
`:. Linewidth =(Dlamda)/(4d)+(Dlamda)/(4d)=(Dlamda)/(2d)`