Question

Interference fringes in Young’s double slit experiment with monochromatic light are:

• A. always equispaced
• B. always unequally spaced
• C. both equally and unequally spaced
• D. formed by a portion of the wave front

Answer 1

The correct option is A always equispaced

Fringe width $=\frac{\lambda D}{d}$
As the $\lambda$ (wavelength), D (distance of screen from the slits) and, d (distance between the slits) remain the same, fringe width remains the same.
Hence all fringes are always equispaced.