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Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsElectrostatic Potential and Capacitance3 Marks
Question
Suppose, one wishes to construct a 1.0 farad capacitor using circular discs. If the separation between the discs be kept at 1.0mm, what would be the radius of the discs?
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Answer

Let the radius of the disc = R

$\therefore$ Area $=\pi\text{R}^2$

$\text{C}=1\text{f}$

$\text{D}=1\text{mm}=10^{-3}\text{m}$

$\therefore\text{C}=\frac{\in_0\text{A}}{\text{d}}$

$\Rightarrow1=\frac{8.85\times10^{-12}\times\pi\text{r}^2}{10^{-3}}$

$\Rightarrow\text{r}^2=\frac{10^{-3}\times10^{12}}{8.85\times\pi}=\frac{10^9}{27.784}$

$=5998.5\text{m}=6\text{Km}$

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