Optics SUB-MENU Optics Sub-menu Problem NoChaptersChapters


651.


Problem 46.3 (RHK)


Monochromatic light of wavelength 441 nm falls on a narrow slit. On a screen 2.16 m away, the distance between the second minimum and the central maximum is 1.62 cm. (a) We have to calculate the angle of diffraction of the second minimum. (b) We have to find the width of the slit.


Solution:           Click For PDF Version

Let the slit width be . For a monochromatic light of wavelength the condition for diffraction minima is

Data of the problem are:

The distance between the second minimum and central maximum is

And, the distance of the screen from the slit is

The angle from the line joining the centre of the slit with the central maximum will be

The angle is small, and we may approximate

.

We note that

or