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2. Electric potential and capacitance — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics2. Electric potential and capacitance1 Mark
MCQ
A capacitor is half filled with a dielectric $(K=2)$ as shown in figure A. If the same capacitor is to be filled with same dielectric as shown, what would be the thickness of dielectric so that capacitor still has same capacity?
  • ✓
    $2 d / 3$
  • B
    $3 d / 2$
  • C
    $3 d / 4$
  • D
    $4 d / 3$
✓

Answer

Correct option: A.
$2 d / 3$
a
(a)

$C_{\text {net }}=\frac{k+1}{2} \frac{A \varepsilon_0}{d}$

$C_{\text {net }}=\frac{A \varepsilon_0}{d-t\left(1-\frac{1}{2}\right)}=\frac{A \varepsilon_0}{d-\frac{t}{2}}$

$C_{\text {net }}=\frac{3 A \varepsilon_0}{2 d}$

$\frac{3 A \varepsilon_0}{2 d}=\frac{A \varepsilon_0}{d-\frac{t}{2}}$

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