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JEE Main 2024 (1 Feb, Shift 2) · Superposition, Coherence & Intensity

Superposition, Coherence & Intensity question from JEE Main 2024 (1 Feb, Shift 2)

Q55JEE Main 2024 · 1 FEB · SHIFT 2Difficult

Superposition, Coherence & Intensity

In Young's double slit experiment, monochromatic light of wavelength 5000 Å is used. The slits are 1.0 mm1.0\text{ mm} apart and screen is placed at 1.0 m1.0\text{ m} away from slits. The distance from the centre of the screen where intensity becomes half of the maximum intensity for the first time is _________ ×10−6 m\times 10^{-6}\text{ m}.

Numerical answer type. Work it out, then open the answer.

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Answer: 125

  1. I=Imax2⇒cos⁡2ϕ2=12⇒ϕ=π2⇒Δx=λ4I = \frac{I_{max}}{2} \Rightarrow \cos^2\frac{\phi}{2} = \frac{1}{2} \Rightarrow \phi = \frac{\pi}{2} \Rightarrow \Delta x = \frac{\lambda}{4}
  2. y=λD4d=5×10−7×14×10−3y = \frac{\lambda D}{4d} = \frac{5\times10^{-7}\times 1}{4\times10^{-3}}
  3. y=1.25×10−4 m=125×10−6 my = 1.25\times10^{-4}\text{ m} = 125\times10^{-6}\text{ m}, so the answer is 125125.
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