Electrostatics Vs Magnetostatics Electrostatics Magnetostatics

Home , Electrostatics, Magnetization, Magnetostatics

Stationary charges ⇒ Constant Electric Field Steady currents ⇒ Constant Magnetic Field

Coulomb’s Law Biot-Savart’s Law

1 ̂ ̂ 4 4

(Inverse Square Law) (Inverse Square Law)

Electric field is the negative gradient of the Magnetic field is the curl of magnetic vector electric scalar potential. potential.

1 ′ ′ ′ ′ 4 |′| 4 |′|

Electric Scalar Potential Magnetic Vector Potential

Three Poisson’s equations for solving Poisson’s equation for solving electric scalar magnetic vector potential potential.

Discrete 2 Physical Dipole ′′′ Continuous

Magnetic Dipole Moment Electric Dipole Moment

1 1 1 3 ∙̂̂ 3 ∙̂̂ 4 4

Electric field cause by an electric dipole Magnetic field cause by a magnetic dipole

Torque on an electric dipole Torque on a magnetic dipole

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Electric force on an electric dipole Magnetic force on a magnetic dipole

∙ ∙

Electric Potential Energy Magnetic Potential Energy of an electric dipole of a magnetic dipole

Electric Dipole Moment per unit volume Magnetic Dipole Moment per unit volume (Polarisation) (Magnetisation)

∙

Volume Bound Charge Density Volume Bound Current Density

∙

Surface Bound Charge Density Surface Bound Current Density

Volume Charge Density Volume Current Density

Net , Free , Bound Net , Free , Bound

Volume Charge Volume Current

Net , Free , Bound Net ,Free , Bound

= Electric field = Magnetic field = Electric Displacement = Auxiliary Field = Dielectric Polaristion = Magnetic Magnetization

Polarisation is proportional to the electric field. Magnetization is proportional to the magnetic field. (Provided the electric field is not too strong) (Provided the magnetic field is not too strong)

Note: Notice that the in is replaced by 1/ and not 1/ in

in dielectric material 1/ in magnetic material in free space 1/ in free space

1 1

Permittivity of dielectric Permeability of material Permittivity of free space Permeability of free space Relative Permittivity Relative Permeability Electric Susceptibility Magnetic Susceptibility Note: Note:  ϵ,ϵ0  , 0

 Electric Susceptibility is a dimensionless  Magnetic Susceptilibity is a dimensionless proportionality constant that indicates the proportionality constant that indicates the degree degree of polarization of a dielectric material in of magnetization of a magnetic material in response to an applied electric field. response to an applied magnetic field.

 0 0 paramagnet M parallel  0 diamagnet M parallel  1 1 paramagnet M parallel  1 diamagnet M parallel

Gauss’s law on net charges Amperes’s law on net current

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