(i) any stationary source charge produces only electric field. When the charge moves with uniform velocity, it produces steady current which gives rise to magnetic field (not time depedent, only space dependent ) around the conductor in which charge flows.
(ii) if the charged particle accelerates, in addition to electric field it also produces magnetic field
(iii) both electric and magnetic fields are time varying. fields. since the electromagnetic waves aret transverse waves, the direction of propagation of electromagnetic waves is perpendicular to the plane containing electric and magnetic field vectors.
(iv) Any oscillatory motion is also an accelerating motion, so, when the charge oscillates (oscillating molecular dipole ) about their mean position as shown in Figure, it produces electromagnetic waves.
(v) Suppose the electromagnetic field in free space propagates along z direction , and if the electric field vector points along y axis then the magnetic field vector will be mutually perpendicular to both electric field and the propagation vector direction, which means
`E_(y) = E sin (kz - omega t)`
`B_(x) = B_(o) sin (Kz - omega t)`
(vi) where, `E_(0) and B_(0)` are amplitude of oscillating electric and magnetic field, k is a wave number, `omega` is the angular frequaency of the
wave and `hat(k)` (unit vector, here it tis called propagation vector ) denotes the direction of propagation of electromagnetic wave.
(vii) Note that both electric field and magnetic field oscillate with a frequency (frequency of electromagnetic wave) which is equal ot the frequency of the source (here, oscillating charge is the source for the productionof electromagnetic waves).
(viii) In free space or in vacuum, the ratio between `E_(0) and B_(0)` is equal to the speed of electromagnetic waves, which is equal to speed of light c.
`c = (E_(0))/(B_(0))`
