SOUND - Important Notes

1. A vibrating body produces sound.
2. Sound has energy
3. Sounds are produced by vibrating bodies and the air that passes through orifices of the instruments.
4. Sound needs a medium to propagate.
5. The to and fro motion of a body from its mean position is known as one vibration.
6. The maximum displacement of vibrating body from its mean position is called as amplitude.
7. The number of vibrations per second is called as frequency.
8. The shrillness of a sound is known as pitch.
9. The pitch of the sound depends upon its frequency.
10. Normal sound consists of mixed frequencies.
11. The sounds which are pleasant to hear are called as music. Music is a combination of sounds that are produced in an order and pleasant to hear.
12. The sounds which are unpleasant to hear are called as noise.
13. The sounds that a normal human being can hear are called as audible sounds.
14. The sounds that a normal human being cannot hear are called inaudible sounds.
15. Frequency of the audible sounds ranges from 20 Hertz (20 vibrations/sec) to 20000 Hertz(20000 vibrations/sec). 

 

Speed of Light faster than sound

Sound is generated due to vibrations in atoms/molecules in a medium and thus always require materialistic medium. The physical parameters like Temperature, Pressure etc., effects the sound velocity.

On the other hand Light doesn't require a materialistic medium. It transmits in space through field.

The concept of field is still a mysterious thing to explain meticulously.

Light is transmitted by 'photons' which are treated as zero mass entity. The speed of sound is negligible when compared to speed of light. This is one of the reasons that while thunderbolts, we see flashing light fast and then hear sound. This is a best example.

In fact light falls in different spectrums and light which gets generated at a point travels through the universe changing its presence int he spectrum.