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  • Two small spheres each of mass 10 mg are suspended from a point by threads 0.5 m long. They are equally charged and repel each other to a distance of 0.20 m. The charge on each of the sphere is <img alt="\frac{a}{21}\times 10^{-8}C." src="https://entra

Two small spheres each of mass 10 mg are suspended from a point by threads 0.5 m long. They are equally charged and repel each other to a distance of 0.20 m. The charge on each of the sphere is \frac{a}{21}\times 10^{-8}C. The value of 'a' will be ______.
[Given g = 10 ms–2]
Option: 1 10
Option: 2 20
Option: 3 30
Option: 4 40

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\begin{array}{l} \mathrm{T} \cos \theta=\mathrm{mg}=10 \times 10^{-6} \times 10=10^{-4} \\\\ \mathrm{~T} \sin \theta=\frac{9 \times 10^{9} \times \mathrm{q}^{2}}{0.04}=\mathrm{F} \\ \\ \tan \theta==\frac{0.1}{\sqrt{0.24}}=\frac{\mathrm{F}}{\mathrm{mg}} \\ \\ \Rightarrow \mathrm{q}=\frac{2 \sqrt{10}}{3 \sqrt{\sqrt{24}}} \times 10^{-8} \\ \\ \Rightarrow q=0.95 \times 10^{-8}=\frac{\mathrm{a}}{21} \times 10^{-8} \\ \Rightarrow \mathrm{a}=20 \end{array}

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Deependra Verma

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