Understanding the concept of LIGHT SOUND


Anything we hear around us is not is sound but vibration of particles. Vibration is a type of disturbance which propagates by particles of medium.

Sound is not travel but it is a wave that is transferred by particles in the form of vibrations (particles can only transfer the vibrations by one particle to second and 2nd to 3rd and so on by remain their positions).

Without particles, sound has no existence. Sound not travel in space because there are no particles in space. , so we transfer the information in form of signal in space.

Speed of sound in different mediums

Air – 343m/sec

Water – 1437m/sec

Glass – 4540m/sec

Iron – 5120m/sec

According to this, as the medium density increases sound speed also increases.

Effect of temperature- As temperature increases speed of sound increases.

The normal range of sound to hear anything for human is 20hz to 20000hz.

But minimum range of sound which a human can hear is 12hz and maximum is 28000hz.

The sound created by a volcano eruption in 1883 is in range of 180decibel and it can be heard up to 3000 miles (ca. 4,828 km).

the sound created by the explosion of nuclear bomb is in range of 240 to 280+ decibels.

So, we cannot imagine what will be the loudest sound.


Light energy is a traveling Photon which is a form of electromagnetic radiation. Photon is a bundle of energy. 

Speed of light is 3 × 10⁸m/sec. in vacuum. 

As dense as the medium the speed of light will decrease.

Nature of light-

Light has dual nature

1- wave nature- we consider the light have wave nature because light has the property of diffraction, refraction, and interference etc.

2-particle nature- light has particle nature because it emits electrons when it strikes on metal surface called Photoelectric effect.

mass of photon is zero.

Formation of light energy -when we provide heat to an object it is start to emit photons.

The number of emitting photons, depending on temperature of the object. 

Photon having a special property that they can never exist in stable form. They start to travel since their formation.

Intensity of light inversely proportional to square of source distance.

7 properties of light – 

reflection, diffraction ,refraction ,polarization, interference ,dispersion, scattering.

Visible light is made up of seven colors known as VIBGYOR.

V – Violet 

I – Indigo

B – blue

G – green 

Y – yellow 

O – orange 

R – red

Where red light has the longest wavelength while violet light has the shortest wavelength.


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