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(b) Satish K. Gupta, p. 735 —
Properties of Electromagnetic waves A few important properties of electromagnetic waves are as given below: 1. Electromagnetic waves propagate in the form of varying
electric and magnetic fields, such that the two fiels are perpendicular to each other and also to the direction of propagation of the wave. In other words, electromagnetic waves are transverse in nature.
Electromagnetic waves are produced by accelerated
charges. 3. Electromagnetic waves do not require any material medium
for their propagation. In free space, electromagnetic waves travel with a velocity.
c= TE= 3 x 10 ms?
100
i.e. with a velocity equal to that of light in free space. In a material medium, velocity of electromagnetic waves is given by
V=
ΜμΕ where u and E are absolute permeability and absolute permittivity of that medium. The electromagnetic waves obey the principle of superposition. The variations in the amplitudes of electric and magnetic fields in the electromagnetic waves always take place at the same time and at the same point in the space. Thus, the ratio of the amplitudes of electric and magnetic fields is always constant and it is equal to velocity of the electromagnetic waves. Mathematically, E
B=0
The energy in electromagnetic waves is divided equally between the electric and magnetic field vectors. The electric vector is responsible for optical effects due to an electromagnetic wave. For this reason, electric vector is called light vector.
100
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TAG WEI 3ich 120-121
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