Question

what is meant by coherent sources of light why are coherent sources required to show interference of light give one example of interference of light from daily life​

Answer 1

Answer

• Two sources are said to be coherent when the waves emitted from them have the same frequency and constant phase difference. Interference from such waves happen all the time, the randomly phased light waves constantly produce bright and dark fringes at every point.
• Two sources of emitting light waves of same frequency or wavelength and of a stable phase difference are required to see interference pattern and we can obtain such nature of light waves from coherent source. So, we require coherent sources to produce the interference of light.
• One of the best examples of interference is demonstrated by the light reflected from a film of oil floating on water. Another example is the thin film of a soap bubble (illustrated in Figure 1), which reflects a spectrum of beautiful colors when illuminated by natural or artificial light sources.