The ratio of intensity at the centre of a bright fringe to the intensity at a point distant (1/4)th of the distance between two successive bright fringes will be (cos 0° = 1, cos 90° = 0) (a) 4 (b) 3 (c) 2 (d) 1

Answer: (c). Moving one fringe width β changes path difference by λ, so β/4 gives Δ x = λ/4, φ = π/2. I = Imaxcos ²φ/2 = Imaxcos ² 45° = Imax2 ImaxI = 2. So the answer is (c) 2.

The ratio of intensity at the centre of a bright fringe to the… | MHT CET 2026 (13 May, Shift 1)

Q9MHT CET 2026 · 13 MAY · SHIFT 1Medium

Superposition, Coherence & Intensity

The ratio of intensity at the centre of a bright fringe to the intensity at a point distant $\left(\frac{1}{4}\right)^{th}$ of the distance between two successive bright fringes will be $(\cos 0^\circ = 1, \cos 90^\circ = 0)$

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Answer: (c)

Moving one fringe width $\beta$ changes path difference by $\lambda$ , so $\beta/4$ gives $\Delta x = \lambda/4$ , $\phi = \pi/2$ .
$I = I_{max}\cos^2\dfrac{\phi}{2} = I_{max}\cos^2 45^\circ = \dfrac{I_{max}}{2}$
$\dfrac{I_{max}}{I} = 2$ . So the answer is (c) $2$ .

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