Question

What path difference produces a bright fringe?

Options

• The angular fringe width, \[\alpha=\frac{\lambda}{d}\]

• An odd multiple of half a wavelength, \[\Delta=\frac{(2m-1)\lambda}{2}\]

• The fringe width, \[\beta=\frac{\lambda D}{d}\]

• An integral multiple of wavelength, \[\Delta=n\lambda\]

Answer 1

Bright fringes result from constructive interference. This occurs when the path difference is an integral multiple of wavelength: \[\Delta=n\lambda\].