Question

If the source of light used in a Young's double slit experiment is changed from red to violet,
(a) the fringes will become brighter
(b) consecutive fringes will come closer
(c) the intensity of minima will increase
(d) the central bright fringe will become a dark fringe

Answer 1

Answer:

answer is option c) the intensity of minima will increase..........

Answer 2

Given that,

If the source of light used in a Young's double slit experiment is changed from red to violet,

We know that,

The intensity of light incidence on the slits is not change.

So, no change in the intensity of the fringes.

We know that,

The fringe width is

$\beta=\dfrac{\lambda D}{d}$

Here, D and d are not change only λ is changed.

$\beta\propto \lambda$

If the wavelength is decreased then the width of fringe will be decrease.

We know that,

The wavelength of the violet color is smaller than the red light.

So, the fringe width will decrease.

Hence, The consecutive fringes will come closer.

(b) is correct option.