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 after the central maximum. If the resultant intensity at P is 2I, what is y(P) in terms of the fringe width β?
Options

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 after the central maximum. If the resultant intensity at P is 2I, what is y(P) in terms of the fringe width β?

Options

G1 Physics · Accepted Answer

For equal slit intensities, 2I = 4I cos²(πΔ ÷ λ). Thus the point is one-quarter fringe width from a bright fringe. Since P lies below the third bright fringe, y(P) = 3β−β ÷ 4 = 11β ÷ 4. Correct option: B.