If you punched a metal plate with two pinholes and illuminated them with light, would you see interference fringes if you used:
(a) laser light, or
(b) light from an LED (light emitting diode) ?
(c) sunlight ?
(d) spontaneous emission coming out the side of the He-Ne laser ?© BrainMass Inc. brainmass.com December 24, 2021, 5:35 pm ad1c9bdddf
SOLUTION This solution is FREE courtesy of BrainMass!
The answer is (a) only
The phenomenon of interference is observed due to superposition of two monochromatic coherent waves, traveling in same direction in the medium.
Monochromatic light means the light of a single wavelength, and coherent means that the phase difference between the waves do not change with time.
(a) The two pinholes are behaving as two secondary sources of light of particular one wavelength hence monochromatic and as they are originating from the same source they are coherent. We can observe interference fringes.
(b) Light from a LED is incoherent, having a narrow spectrum and hence the fringes of different wavelengths overlapped, due to which we can't observe the phenomenon.
(c) The sun light is having continuous spectrum means all possible wavelengths, hence not possible
(d) In this case number of wavelengths is emitted as well as the regular emission is not there hence fringes are not observed.© BrainMass Inc. brainmass.com December 24, 2021, 5:35 pm ad1c9bdddf>