Question

A diffraction pattern is produced on a viewing screen by illuminating a long narrow slit with light of wavelength λ. If  λ is increased and no other changes are made:

A.) the intensity at the center of the pattern decreases and the pattern expands away from the bright center

B.) the intensity at the center of the pattern does not change and the pattern expands away from the bright center

C.) the intensity at the center of the pattern increases and the pattern contracts toward the bright center

D.)the intensity at the center of the pattern does not change and the pattern contracts toward the bright center

Answer 1

Whwn we increase the wavelength the bending of light decreases at the edges of the slit, which is more important to create the waves with different phases causes to interference will affect and gte reduces because of increasing wavelength. So intensity at the cnetre gets decreases because it spreads out from the centre. We wont get sharp peak at the centre.

Suppose if we send a light of blue and red color, because of blue is short wavelength it bends more than red.

Answer is A

The intensity at the center of the pattern decreases and the pattern expands away from the bright center