A repulsive force force of 220 N exists between an unknown charge and a charge of +4.7mC.

1. A repulsive force force of 220 N exists between an unknown charge and a charge of +4.7mC. If they are separated by 2.5cm, what is the magnitude of the unknown charge?

A uniformly charged CD spins counter clockwise in the x-y plane. Determine magnetic moment.

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Poynting vector and power dissipation

Consider the integral of the inwardly directed normal component of the Poynting vector over a surface S bounding a volume V of a linear, isotropic, homogeneous, conducting medium. Show that this quantity can be indentified with the sum of the rate of change of the electromagnetic energy and the power dissipated when there is a f ...continues

To find the value and direction of the Poynting vector at the surface of a current carrying wire and show that the total power entering the wire per unit length is (I^2)R.

A straight conducting wire of circular cross section, radius a, has a resistance R per unit length and carries a constant current I. Find the value and direction of the Poynting vector at the surface of the wire, and hence show that the total power entering the wire per unit length is (I^2)R. By considering the divergence of the ...continues

Show that the field inside a spherical cavity cut in a uniform dielectric medium is uniform and of magnitude Ecav = 3erEm/(2Er+1), where er is the relative permittivity of the medium and Em is the uniform field in the dielectric at a point distant from the cavity.

Show that the field inside a spherical cavity cut in a uniform dielectric medium is uniform and of magnitude Ecav = 3erEm/(2Er+1), where er is the relative permittivity of the medium and Em is the uniform field in the dielectric at a point distant from the cavity.

How do you find electric energy density and magnetic energy density?

How do you find electric energy density and magnetic energy density?

Electromagnetism: C and L of a parallel wire line, E and B fields between 2 parallel wires

I need to find the capacitance and inductance per unit length between 2 parallel wires. To do this, I have to calculate the E and B fields between the 2 wires, each with radius a, separated by d, where d is much bigger than a? Could you please show the whole derivation? (I assume you'd use Gauss' and Amperes' law but I could nev ...continues

Telegraph equations

Could you please show me how to derive the telegraph equations for a loss-less transmission line? Also, please solve this problem: A loss-less transmission line of characteristic impedance Z0 is terminated by a resistive load R. Find an expression for the input impedance of a section of the line of length l. Show that this ...continues

A plane electromagnetic wave is incident at angle on the boundary plane separating two non-magnetic media, with the electric vector in the plane of incidence. To show that wave reflected from the boundary has the same frequency as the incident wave and angle of reflection is equal to the angle of incidence. Also, derive an expression for the power reflection coefficient in this case.

A plane electromagnetic wave is incident at angle theta to the normal on the boundary plane separating two non-magnetic media with relative permitivities e1 and e2. For the case in which the electric vector is in the plane of incidence, show that any wave reflected from the boundary has the same frequency as the incident wave. S ...continues

Complex refractive index and power reflection coefficient

Show that the complex refractive index of a conducting medium can be expressed as n = λ0(1+i)/2πδ and n = λ0(1-i)/2πδ where δ is the skin depth. Hence find the power reflection coefficient for an EM wave incident from free space on a good non-magnetic conductor at normal incidence. Show that ...continues