Two slits in an opaque barrier each have a width of 0.020 mm and are separated by 0.050 mm.When coherent monochromatic light passes through the slits the number of interference maxima within the central diffraction maximum:
A)is 1
B)is 2
C)is 4
D)is 5
E)cannot be determined unless the wavelength is given

Question

Quizplus · Accepted Answer

The number of interference maxima within the central diffraction maximum can be determined by the ratio of the slit separation to the slit width. Here, the separation is 0.050 mm and the width is 0.020 mm. The ratio is 0.050/0.020 = 2.5. This means 2 complete sets of maxima fit within the central maximum, plus the central maximum itself, totaling 5 maxima (2 on each side of the central maximum plus the central maximum).

Two Slits in an Opaque Barrier Each Have a Width