Electrostatics

JEE Main level, numerical answer, medium

107 of 311

Question 107 of 311

The peak electric field produced by the radiation coming from the 8W8W bulb at a distance of 10m10m is x10μ0cπVm−1\dfrac{x}{10}\sqrt{\dfrac{{\mu }_{0}c}{\pi }}V{m}^{-1}. The efficiency of the bulb is 1010% and it is a point source. The value of xx is,

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Answer: 2

I=12cϵE020I=\dfrac{1}{2}c\epsilon E020
84π×102×12=14×c×1μ0c2×E02\dfrac{8}{4\pi \times {10}^{2}}\times \dfrac{1}{2}=\dfrac{1}{4}\times c\times \dfrac{1}{{\mu }_{0}{c}^{2}}\times {E}_{0}^{2}
E0=210×μ0cπ⇒x=2{E}_{0}=\dfrac{2}{10}\times \sqrt{\dfrac{{\mu }_{0}c}{\pi }}\Rightarrow x=2

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