In a Young's double-slit experiment, each slit individually produces intensity I. A point P on the positive-y side lies between the third dark fringe and the third bright fringe, and the resultant intensity at P is 2I. If the path difference at P is written as Nλ ÷ 4, find N.
Physics · Wave Optics · young's dubble slit experiments
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Question

In a Young's double-slit experiment, each slit individually produces intensity I. A point P on the positive-y side lies between the third dark fringe and the third bright fringe, and the resultant intensity at P is 2I. If the path difference at P is written as Nλ ÷ 4, find N.

Physics · Wave Optics · young's dubble slit experiments

G1 Physics · Accepted Answer

For intensity 2I, the point is one-quarter fringe away from a bright fringe. The third bright fringe corresponds to Δ = 3λ. Since P lies below it, Δ(P) = 3λ−λ ÷ 4 = 11λ ÷ 4. Thus, N = 11.