Question bank/JEE Main/Physics

JEE MainPhysicsDifficultElectrostatics

[IMAGE] A and d are the plate area and distance between plates of a parallel
plate capacitor repectively. The dielectric constant of dielectric

filled inside a parallel plate capacitor is variable and given as

k(x)=K(1+γxk(x) = K(1 + \gamma x) where is the distancemeasured from the
left plate as shown in the figure. If
(γd)<<1(\gamma d) < < 1, then find the
capacitance of capacitor with dielectric.

Show answer and solution
Capacitance of element=kε0Adx= \frac{k\varepsilon_{0}A}{dx}
∑1C′=∫0d\mspace2mudxKε0A(1+γx)\sum\frac{1}{C^{'}} = \int_{0}^{d}\mspace{2mu}\frac{dx}{K\varepsilon_{0}A(1 + \gamma x)}
1C=1Kε0Aαln(1+γd)\frac{1}{C} = \frac{1}{K\varepsilon_{0}A\alpha}ln(1 + \gamma d)
{\ Given\ \ \gamma d < < 1C = \right)$$

Source: Grass-G / P-20 Physcis Paper 12 Dec.docx

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