# A source of light having wavelength 5500a.u is falls normally on slit a width of 22*1/100000cm.calculate the angular seperation of the first two minima on either side of central maxima.

2
by rishithasona26
What's the separation between screen and source?
Oh! Sorry it isn't needed. My mistake.

• Brainly User
2014-11-24T19:44:16+05:30
You need the fringe length ß = λD/d. And angular separation is θ = ß/D = λ/d = (55/22)/(10) = 0.25 radians
2014-11-25T04:03:53+05:30

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You should write the wavelength as °A  (Angstroms)  and not as a.u.  the unit a.u. is used in astronomy and it is very large.

In the single slit experiment of Young, we have the angle Ф of the minimum intensities on the screen with respect to the perpendicular bisector of the slit as:

sin Ф ≈ Ф ≈ n λ / a ,  n = +- 1, +- 2, +- 3,....
where λ = wavelength of the light wave of single frequency
a = single slit width

hence the angular separation of the first two minima = 2λ/a - λ/a = λ/a
= 5500 * 10⁻⁸ cm / 22 * 10⁻⁵ cm
= 0.25 radians = 14.32 degrees

click on thank you.