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
|