Question
Question: Given below are two statements: **Statement 1:** No sustained interference pattern is obtained when...
Given below are two statements:
Statement 1: No sustained interference pattern is obtained when two electric bulbs of the same power are taken.
Statement 2: Phase difference between waves coming out of electric bulbs is not constant.
Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-1.
Statement-1 is true, Statement-2 is true; Statement-2 is not the correct explanation of statement-1
Statement-1 is false, Statement-2 is true.
Statement-1 is true, Statement-2 is false.
Statement-1 is true, Statement-2 is true; Statement-2 is the correct explanation of Statement-1.
Solution
Interference patterns are observed only from coherent sources, which means the phase difference between the waves emitted by the sources must remain constant over time. Electric bulbs produce light through thermal emission, which is an incoherent process. The light waves emitted from different atoms within the bulb are independent, leading to a random and rapidly fluctuating phase difference between the waves from any two points or any two bulbs. Therefore, electric bulbs are not coherent sources. Statement 1 is true because sustained interference requires coherent sources, and electric bulbs are not coherent. Statement 2 is true because the phase difference between waves coming out of electric bulbs is indeed not constant due to the incoherent nature of light emission from incandescent sources. Since the lack of a constant phase difference (incoherence) is the fundamental reason why sustained interference patterns cannot be obtained from electric bulbs, Statement 2 correctly explains Statement 1.