A capacitor is made with a polymeric dielectric having εr of 2.26 and a dielectric breakdown strength of 50 kV / cm. The permittivity of free space is 8.85 pF / m. If the rectangular plates of the capacitor have a width of 20 cm and a length of 40 cm, the maximum electric charge in the capacitor is
8 μC
At breakdown, \(Q_{max}=\varepsilon_0\varepsilon_rAE_{max}\). Here \(A=0.2(0.4)=0.08\,m^2\) and \(E_{max}=50\,kV/cm=5\times10^6\,V/m\). Hence \(Q_{max}=8.85\times10^{-12}(2.26)(0.08)(5\times10^6)\approx8\,\mu C\).
Important Questions from Electrostatics
A uniform ring charge of radius $R$ carries a total charge $Q$. Which one of the following options correctly quantifies the magnitude of the force on a point charge of strength $q$ kept at the center of the ring?
($\epsilon$ is the permittivity of the medium)
For a uniform line charge of 8 nc/m lying along the z axis, the electric field at a radius of 3 m from the uniform line is given by :
The current in a coil of inductance 5 H changes linearly from 10 A to 2 A in t seconds. If the induced emf is 40 V, what is the time t?
What are the materials which exhibit electric polarization even in the absence of an applied electrical field?
What is the relative permittivity of slate dielectric?
