Question

Tell me about Conditions of interference ??

Answer 1

We know that the superpositions of two mechanical waves can
be constructive or destructive. In constructive interference, the
amplitude of the resultant wave at a given position or time is
greater than that of either individual wave.
If two light bulbs are placed side by side, no interference
effects are observed because the light waves from one bulb
are emitted independently of those from the other bulb. The
emissions from the two light bulbs do not maintain a constant
phase relationship with each other over time. Light waves from
an ordinary source such as a light bulb undergo random phase
changes in time intervals less than a nanosecond. Therefore,
the conditions for constructive interference, destructive
interference, or some intermediate state are maintained only
for such short time intervals. Because the eye cannot follow
such rapid changes, no interference effects are observed. Such
light sourees are said to be incoherent
conditions must be met:
In order to observe interference in light waves, the following
1. The sources must be coherent -that is. they must
2. The source should be monochromatic -that is, of a
maintain a constant phase with respect to each other.
single wavelength.