In capacitors, using a dielectric between the plates required a change in the ca

Question

In capacitors, using a dielectric between the plates required a change in the calculations. The more polar the material, the larger the permittivity, because the dipoles would line up in the field and decrease the electric field for a given charge. Similarly, when a substance other than vacuum fills the core of an inductor, the permeability of the material, = o(1+m), should be used in place of o in the calculations. The table below gives the magnetic susceptibilities, Xm, for a few materials. Nitrogen, Diamond and Hydrogen are all diamagnetic, having no unpaired electrons. Oxygen has 2 unpaired electrons. Ferrite is ferromagnetic. The value given is a typical value.

(a) Describe why we treat air the same as vacuum for approximate work.

(b)Given the data in the table, can you describe the effect of the materials on the magnetic field in the inductor?

Material Xm
Aluminium 2.3 x 10-5
Copper -0.98 x 10-5
Diamond -2.2 x 10-5
Tungsten 6.8 x 10-5
Hydrogen (1 atm) -0.21 x 10-8
Oxygen (1 atm) 209.0 x 10-8
Nitrogen (1 atm) -0.50 x 10-8
Ferrite (soft, Zn-Mn) 104

- I believe that its due to the minimal changes and effects that accounting for everything would have vs. the amount of calculation required.

- and I'm still working on part 2.... Any help is appreciated! Thanks!

Explanation / Answer

The dielectric constant k is the relativepermittivity of a dielectric material

for vaccum it is 1.00000. for air it is 1.00059 hence we treat air as vaccum

also, inserting material with high Xm will increase inductance. for example, introducing a ferrite core in 1 H inductor will change its inductance to 105 H

( ferrite is often used in inductors to reduce their size )

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