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Capacitors — Physics STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 SciencePhysicsCapacitors2 Marks
Question
A cylindrical capacitor is constructed using two coaxial cylinders of the same length 10cm and of radii 2mm and 4mm:
  1. Calculate the capacitance.
  2. Another capacitor of the same length is constructed with cylinders of radii 4mm and 8mm. Calculate the capacitance.
✓

Answer

  1. $\text{C}=\frac{2\epsilon_0\text{L}}{\text{ln}\big(\frac{\text{R}_2}{\text{R}_1}\big)}=\frac{\text{e}\times3.14\times8.85\times10^{-2}\times10^{-1}}{\text{ln}2}$ $[\text{ln 2}=0.6932]$
$=80.17\times10^{-13}$
$\Rightarrow8\text{PF}$
  1. Same as $\frac{\text{R}_2}{\text{R}_1}$ will be same.

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