Aparallel plate capacitor is to be designed with a voltage rating 1kV, using a material of dielectric constant 3 and dielectric strengthabout 107Vm−1.(Dielectric strength is the maximum electric field a material cantolerate without breakdown, i.e., without starting to conductelectricity through partial ionisation.) For safety, we should likethe field never to exceed, say 10% of the dielectric strength. Whatminimum area of the plates is required to have a capacitance of 50pF?
Aparallel plate capacitor is to be designed with a voltage rating 1kV, using a material of dielectric constant 3 and dielectric strengthabout 107Vm−1.(Dielectric strength is the maximum electric field a material cantolerate without breakdown, i.e., without starting to conductelectricity through partial ionisation.) For safety, we should likethe field never to exceed, say 10% of the dielectric strength. Whatminimum area of the plates is required to have a capacitance of 50pF?
Potential rating of aparallel plate capacitor, V = 1 kV = 1000 V
Dielectric constant ofa material, 
=3
Dielectric strength =107 V/m
For safety, the fieldintensity never exceeds 10% of the dielectric strength.
Hence, electric fieldintensity, E = 10% of 107 = 106 V/m
Capacitance of theparallel plate capacitor, C = 50 pF = 50 ×10−12 F
Distance between theplates is given by,
Where,
A = Area of eachplate
= Permittivity of free space =
Hence, the area of eachplate is about 19 cm2.
Potential rating of aparallel plate capacitor, V = 1 kV = 1000 V
Dielectric constant ofa material, =3
Dielectric strength =107 V/m
For safety, the fieldintensity never exceeds 10% of the dielectric strength.
Hence, electric fieldintensity, E = 10% of 107 = 106 V/m
Capacitance of theparallel plate capacitor, C = 50 pF = 50 ×10−12 F
Distance between theplates is given by,
Where,
A = Area of eachplate
= Permittivity of free space =
Hence, the area of eachplate is about 19 cm2.
