Question

(a) In a single slit diffraction experiment, a slit of which ‘d’ is illuminated by red light of wavelength 650nm. For what value of ‘d’ will: 

(i) the first minimum fall at an angle of diffraction of 30°, and 

(ii) the first maximum fall at an angle of diffraction of 30°? 

(b) Why does the intensity of the secondary maximum become less as compared to the central maximum?

Answer 1

(a) (i) For nth minima, dsinθ =nλ

(b) To produce secondary maxima, the wavelets from lesser and lesser part of slit produce constructive interference.