Electromagnetic Waves Class 12 | Electromagnetic Waves Class 12 Notes
Electromagnetic Waves Class 12 | Electromagnetic Waves Class 12 Notes :- In the chapter “Moving Charges and Magnetism” we saw that magnetic field is produced due to electric current and in the chapter “Electromagnetic Induction” we saw that “electric field” is produced due to “varying magnetic field”. But, is the opposite also true? That is, can a changing “electric field” generate a “magnetic field”?
In the year 1864, James Clark Maxwell (1831-1879) imagined that a magnetic field could be generated from a changing electric field. According to Maxwell, if an electric charge oscillates, it will emit electromagnetic waves. The reason for this is that an oscillating charge is in an accelerated state, hence its velocity will change with time and the magnetic field produced by it will also change with time. Now this changing magnetic field will generate an electric field, this electric field will also keep changing with time. Both the variable fields will be perpendicular to each other as well as to the direction of wave propagation. The frequency of these fields will be equal to the frequency of the oscillating charged particle and they will be in the same phase.
On the basis of this assumption, Maxwell gave some mathematical equations which are called Maxwell’s equations. Electromagnetic phenomena can be explained on the basis of these equations.