In order to produce several visible interference fringes from two narrow slits using light of a single wavelength, the distance between the slits must be of the order
A) of a few tenths of the wavelength.
B) of a few wavelengths.
C) of a few tens wavelengths.
D) of a few hundreds wavelengths.
E) the distance does not matter.

Question

Quizplus · Accepted Answer

In order to produce visible interference fringes, the distance between the slits must be of the order of a few wavelengths. This is because interference only occurs when the path difference between the waves from the two slits is of the order of the wavelength. If the distance between the slits is only a few tenths of the wavelength, the path difference will not be significant enough to produce visible interference fringes. On the other hand, if the distance between the slits is much larger (a few hundred wavelengths or more), the diffraction patterns from each slit will overlap significantly and the interference pattern will not be well-defined. Therefore, the best choice is B – of a few wavelengths.

In Order to Produce Several Visible Interference Fringes from Two