NEET Physics Question - Wave Optics - Young's Double Slit Experiment

Assertion (A): If two sodium lamps are used illuminating two pinholes, interference fringes will not be observed.

Reason (R): Light waves coming from an ordinary source like sodium lamp are unpolarised in nature.

Both (A) & (R) are true and the (R) is the correct explanation of the (A)

Both (A) & (R) are true but the (R) is not the correct explanation of the (A)

(A) is true but (R) is false

Both (A) and (R) are false

Solution:

Assertion (A) is true: Two independent sources (like sodium lamps) are incoherent, meaning they do not maintain a constant phase relationship, thus cannot produce a stable interference pattern. Reason (R) is true: Light from ordinary sources like sodium lamps is unpolarised. However, incoherence is the primary reason for no interference, not the unpolarised nature. Thus, (R) is not the correct explanation for (A).

Rankers Physics

Interference with two sodium lamps

Solution:

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