To set up a stable and clear interference pattern, two conditions must be met: The sources of the waves must be coherent, which means they emit identical waves with a constant phase difference. The waves should be monochromatic – they should be of a single wavelength.

inhibition, which can be either retroactive or proactive. In retroactive inhibition, new learning interferes with the retention of old memories; in proactive inhibition, old memories interfere with the retention of new learning. Both phenomena have great implications for all kinds of human learning.

What is Interference? Wave interference is the phenomenon that occurs when two waves meet while traveling along the same medium. The interference of waves causes the medium to take on a shape that results from the net effect of the two individual waves upon the particles of the medium.

Expert Answer:

• Coherent sources: Two sources are said to be coherent in nature if they emit light of same frequency and of a stable path difference.
• Conditions for sustained interference pattern:
• The two sources of light must be coherent with same frequency or wavelength and with same phase or constant phase difference.

No, the two identical and independent sodium lamps do not act as coherent sources because the phase difference between waves emitted will change randomly and sustained interference will not be possible.

We are getting interference of the waves from the two slits, but the waves from each of the slits have a non-uniform strength as y changes due to the one-slit pattern. You are interference waves from two slits, but waves of 0 intensity — so the total result is zero.

Sustained interference means positions of maxima and minima of light intensity remain fixed throughout the screen. The intensity of the light remains same throughout. In case of sustained interference the phenomenon of interference is permanent. Therefore sustained interference is also known as permanent interference.