Question

(a) Can the displacement current exist in vacuum? Briefly explain. (2 points) (b) Consider a medium with dielectric permittivity є, magnetic permeability k. The conductivity ơ--O. If the magnetic field in this medium is H = H0 sin (at-kz)as, where-=--, find the electric field . You can assume that at t = 0, E = 0 at z = 0 (4 points) (c) The displacement current causes magnetic field in the same way conduction current does. True or false? Choose the correct answer and briefly explain. (2 points)

Answer 1

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No see above expression of Jd (displacement current density ) whicht is non zero if there are time varying electric feild .

We know EM wave can travel via vaccum...thus it is time varying feild hence Jd will be non zero for vaccum means there is displacemnet current exixts even in vaccum.

Answer (b)

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answer (c)

See in part a it is written(conduction current) Jc=conductivity *electric feild .

Means current due to Jc is due to static ELectric feild or static charges

While displacement current density(Jd)is function is time varying electric feild ....Thus both the cause of production of magnetic feilds are different

hence magnetic feild produce by conduction current and displacement current is differen ..

ABove statement is false.