Today we will discuss electric lines of forces and their properties.
Definition of Electric line of force: An electric line of force is a path, straight or curved, such that tangent to it at any point gives the direction of electric field intensity at that point.
In Fig. 1, PQ is an electrostatic line of force. The tangent to the line at any point A gives the direction of electric intensity EA at A. Similarly, tangent to PQ at B gives the direction of EB, (see Figure)
Let us discuss the direction of electric field lines for different types of charges:
Hello friends, last time we have discussed about electric flux and its units. Similarly in magnetism, there is concept of magnetic flux. Have you imagined, why a magnet able to attract an iron piece place near by it but if the iron piece is placed somewhat far away from magnet then magnet is not able to attract it.
Ans: We know that a charge at rest produces an electric field around it but no magnetic field where a moving charge produces both electric and magnetic fields but if the charge is moving with constant velocity there will be no charge in the values of the electric and magnetic fields,So all electromagnetic waves are produced.Now if charge is moving with non zero acceleration, both the electric and magnetic field will change, there by producing the em waves. So we conclude that an accelerated charge emits electromagnetic waves. Continue reading “Electromagnetic waves and their features”
Last time I have discussed the few characteristics or properties of transverse electric and magnetic waves in parallel planes. Let us discuss more properties of TE and TM waves like cut-off wavelength, guide wavelength, phase velocity, group velocity:
DEFINITION TRANSVERSE MAGNETIC (TM) WAVES OR E WAVES :
In this case, the component of magnetic field vector H lies in the plane transverse to the direction of propagation that is there is no component of H along the direction of propagation where as component of electric field vector E lies along the direction of propagation.
Derivation transverse magnetic waves between parallel planes:
As the direction of propagation is assumed as z-direction, therefore,
Hz = 0, Ez not equals to 0
By substituting Hz = 0 in equation, we get
Hx = 0, Ey = 0,and Ex not equals to 0, Hy not equals to 0
DEFINITIONTRANSVERSE ELECTRIC (TE) WAVES OR H WAVES IN PARALLEL PLANES:
In the case, the component of electric field vector E lies in the plane transverse to the direction of propagation that is there is no component of E along the direction of propagation where as a component of magnetic field vector H lies along the direction of propagation.
Derivation of transverse electric waves in parallel planes:
As the direction of propagation is assumed as z-direction, therefore
Ez = 0 and Hz is not equal to 0
Now by substituting Ez = 0 in equation (8) of article “waves between parallel planes”, we get
Ex= 0 and Hy = 0 and
Ey not equals to 0 , Hx not equals to 0
Now write wave equations for free space in terms of E
Statement. This theorem states that the cross product of electric field vector, E and magnetic field vector, H at any point is a measure of the rate of flow of electromagnetic energy per unit area at that point, that is