Hi
There is almost one-to-one correspondence between magnetic and electric fields. It is not very surprising in view of the fact that one cannot exist without the other, they are like twins. Please note that I don't need very rigorous approach towards these concepts because I have just started learning all this stuff. Thanks.
The term magnetic field can refer to two closely related fields: B and H. B is also called magnetic flux density or magnetic induction. Likewise, H is often called magnetic field intensity. But, in my view, calling them H-field and B-field is a rather good choice.The distinction between the two is important. This page could be quite helpful for this. Summarily, H is the field actually generated by electric current while B is enhanced magnetic field due to response of some other material. In other words, H could be said as 'causative field' and B as 'responsive field'. For example, if a solenoid has an iron core, it's magnetic field is increased manifolds.
Both vector fields are related: B=μH, where μ is called permeability or magnetic constant of a material. As it is obvious from the relation that both fields point in the same direction. The magnetic constant of free space or vacuum is 4π × 10−7 H/m. It means that free space will increase the H field by 4π × 10−7 factor.
Q1: Is there any material which does not affect the H field and leave it as it is. In such a case, μ would be unity. Metglas has μ=1.25. For superconductors μ=0.
A similar relation also exists for electric field, D=εE, where ε is permittivity of the medium. For free space ε0 = 8.85 × 10−12 F/m. Here one thing should be keep in mind that permittivity is is the measure of the resistance that is encountered when forming an electric field in a medium. Therefore, higher the permittivity, the higher the resistance. In layman terms, D is charge density on a surface (charge could be negative or positive), and this charge density gives rise to electric field E. D is very similar to H in that in case of the H the product "nxI" determines the strength of H (H=nI, where "n" is number of turns per unit length and "I" is current) while in case of D quantity of charge per unit area determines its strength. More charge density means strong electric field. So, it can be said D is 'causative field' and 'E' is responsive field.
Q2: This question is quite similar to Q1. Is there any material which neither resist electric field not enhance it? Even free space has some resistivity to offer to the electric field.
Thank you for the help.
The following link(s) could be useful to someone like me:
1: http://www.ie.itcr.ac.cr/acotoc/Mae..._Comunicacion_II/Material/Biblio2/chapt03.pdf
2: http://www.antenna-theory.com/definitions/electricfluxdensity.php
Regards
PG
There is almost one-to-one correspondence between magnetic and electric fields. It is not very surprising in view of the fact that one cannot exist without the other, they are like twins. Please note that I don't need very rigorous approach towards these concepts because I have just started learning all this stuff. Thanks.
The term magnetic field can refer to two closely related fields: B and H. B is also called magnetic flux density or magnetic induction. Likewise, H is often called magnetic field intensity. But, in my view, calling them H-field and B-field is a rather good choice.The distinction between the two is important. This page could be quite helpful for this. Summarily, H is the field actually generated by electric current while B is enhanced magnetic field due to response of some other material. In other words, H could be said as 'causative field' and B as 'responsive field'. For example, if a solenoid has an iron core, it's magnetic field is increased manifolds.
Both vector fields are related: B=μH, where μ is called permeability or magnetic constant of a material. As it is obvious from the relation that both fields point in the same direction. The magnetic constant of free space or vacuum is 4π × 10−7 H/m. It means that free space will increase the H field by 4π × 10−7 factor.
Q1: Is there any material which does not affect the H field and leave it as it is. In such a case, μ would be unity. Metglas has μ=1.25. For superconductors μ=0.
A similar relation also exists for electric field, D=εE, where ε is permittivity of the medium. For free space ε0 = 8.85 × 10−12 F/m. Here one thing should be keep in mind that permittivity is is the measure of the resistance that is encountered when forming an electric field in a medium. Therefore, higher the permittivity, the higher the resistance. In layman terms, D is charge density on a surface (charge could be negative or positive), and this charge density gives rise to electric field E. D is very similar to H in that in case of the H the product "nxI" determines the strength of H (H=nI, where "n" is number of turns per unit length and "I" is current) while in case of D quantity of charge per unit area determines its strength. More charge density means strong electric field. So, it can be said D is 'causative field' and 'E' is responsive field.
Q2: This question is quite similar to Q1. Is there any material which neither resist electric field not enhance it? Even free space has some resistivity to offer to the electric field.
Thank you for the help.
The following link(s) could be useful to someone like me:
1: http://www.ie.itcr.ac.cr/acotoc/Mae..._Comunicacion_II/Material/Biblio2/chapt03.pdf
2: http://www.antenna-theory.com/definitions/electricfluxdensity.php
Regards
PG