Question

Condition for getting the bright fringes when the optical path difference of beams is equal to - ???​

Answer 1

Answer:

Constructive interference at a point between the two waves takes place if the path difference between the waves at that point is equal to integral multiple of wavelength of the waves.

So, path difference Δx=nλ

where n must be an integer

Answer 2

Fringes are formed during the interference of light waves.

• The interference pattern formed during the coincidence of crests of two different waves is called the bright fringe.
• Young's double slip experiment helped to study and obtain the conditions for fringe formation during interference.

Conditions for the formation of bright fringes:

If 'λ' is the wavelength of the light waves, 'D' is the distance between the screen and light source, and 'd' is  the distance between the slits, then;

1. Path difference between the light waves has to be 'nλ', where 'n' can be zero or integers.

2. The distance of the bright fringe from the center has to be;                

               $x_{n}$ = (nλD) /d  ⇒ eq. 1, where 'n' is the $n_{th}$ bright fringe.

       Similarly, for the  $(n-1)_{th}$ bright fringe,

               $x_{n-1}$ = (n-1)λD /d  ⇒ eq. 2

3. The fringe width of the bright fringe has to be;

                β = λD /d  ( eq.2 - eq.1 )