Electromagnetic Waves

The quality of a musical sound is that characteristic which distinguishes between two sounds of the same frequency and same intensity but emitted by different musical instruments. The quality of sound depends upon the number, order and relative intensity of the overtones. Hence, quality of sounds produced by different instruments differ from instrument to instrument. Therefore, quality of sound is dependent on frequency.

Number of beats per second difference of the frequencies of sound sources. Let be the length of pipe and is the velocity of sound, then the frequency of note emitted from the pipe is

Number of beats in For a closed organ pipe

In , Maxwell on mathematical back ground assumed that an oscillating electric charge produces the electromagnetic waves of frequency equal to the frequency of oscillations of the charge. Hertz, in , experimentally found that an oscillating electric charge produces the electromagnetic waves. Then in , J.C. Bose experimentally produced the electromagnetic waves of wavelength in the range of to nearly. Then in , Marconi could send the electromagnetic waves upto a distance of nearly by transmitting them through antenna. Thus, Hertz first experimentally proved the existance of electromagnetic waves.

The rms speed of molecules of gas is The average speed of molecules of gas is also the most probable speed of molecules of gas is By observing Eqs. (i), (ii) and (iii), we conclude that