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Wave Optics Part 1

Section: Physics

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Question : 64 of 100

Marks: +1, -0

In a double-slit experiment, green light (5303 Å) falls on a double slit having a separation of 19.44 m and a width of 4.05 µm. The number of bright fringes between the first and the second diffraction minima is :-

[11 Jan 2019 Shift 2]

09
10
04
05

Solution:

For diffraction

location of 1st minime

y_1

=

\frac{D\lambda}{a}

= 0.2469 Dλ

location of 2nd minima

y_2

=

\frac{2D\lambda}{a}

= 0.4938 Dλ

Now for interference

Path difference at P.

\frac{dy}{D}

= 4.8 λ

path difference at Q

\frac{dy}{D}

= 9.6 λ

So orders of maxima in between P & Q is5, 6, 7, 8, 9

So 5 bright fringes all present between P & Q.

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