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JEE Main 2021 (22 Jul, Shift 2) · Energy Density & Intensity

Energy Density & Intensity question from JEE Main 2021 (22 Jul, Shift 2)

Q21JEE Main 2021 · 22 JUL · SHIFT 2Medium

Energy Density & Intensity

Intensity of sunlight is observed as 0.092 Wm−2{}^{-2} at a point in free space. What will be the peak value of magnetic field at the point?

(ε0=8.85×10−12C2N−1m−2\varepsilon_0 = 8.85 \times 10^{-12} C^2 N^{-1} m^{-2})

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Answer: (a)

  1. E0=2Iε0c=0.1848.85×10−12×3×108=69.3≈8.32E_0 = \sqrt{\dfrac{2I}{\varepsilon_0 c}} = \sqrt{\dfrac{0.184}{8.85 \times 10^{-12} \times 3 \times 10^{8}}} = \sqrt{69.3} \approx 8.32 V/m
  2. B0=E0c=8.323×108≈2.77×10−8B_0 = \dfrac{E_0}{c} = \dfrac{8.32}{3 \times 10^{8}} \approx 2.77 \times 10^{-8} T
  3. So the answer is (a) 2.77×10−82.77 \times 10^{-8} T.
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