Question

In Young’s double slit experiment the distance between the slits and the screen is doubled. The separation between the slits is reduced to half. As a result the fringe width(a) is doubled(b) is halved(c) becomes four times(d) remains unchanged

Answer 1

Answer:

C) The fringe width becomes four times.

Explanation:

Fringe width β = Dλ/d

where D is the distance between slits and screen  

and d is the distance between the slits.

Thus, From qn D’ = 2D and d’ = d/2

When D is doubled and d is reduced to half, then  the fringe width becomes

β’ = λ2D/ (d/2)

= 4λD/d

= 4β

Thus, when the double slit experiment the distance between the slits and the screen is doubled and the separation between the slits is reduced to half, the fringe width becomes four times.