# 12 Difference Between Light And Sound Waves

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## Light Waves

Light travels as waves. Light waves don’t always require particles to travel through. They can also travel through outer space or a vacuum. Light waves travel in straight lines. You can detect them with your eyes and also with instruments such as camera. They are reflected by mirrors and change direction when they travel from the air into glass or water. Light waves travels at much higher velocity as compared to sound waves. The velocity of light waves through a vacuum is 2.998 x 108 m/s. It only takes 8 minutes and 20 seconds for light to travel from the source (Sun) to the Earth.

Given that light is a wave, as such it can be described as having a frequency and a wavelength. The wavelength of light is the distance between corresponding points in two adjacent light cycles. Visible light has a wavelength of range from 400-700nm, Violet light has a wavelength of 400nm while red light has a wavelength of 700nm. The frequency of light is the number of cycles of light that pass a given point in one second. Violet light has a frequency of 7.5 x 1014  Hz whereas red light has a frequency of 4.3 x 1014Hz. Light waves are of different frequencies, resulting in different colors.

### What You Need To Know About Light Waves

• Light wave can be considered to be made of waves as well as particles.
• Light waves are electromagnetic or transverse waves consisting of varying electric and magnetic fields.
• Light waves do not require a material medium for propagation. The waves can travel in a vacuum.
• Light waves are of different frequencies, resulting in different colors.
• Light propagates by a chain reaction of electric and magnetic fields recreating each other.
• Light waves can travel through a much greater distance.
• Light waves travels at much higher velocity as compared to sound waves. The velocity of light waves through a vacuum is 2.998 x 108 m/s.
• Visible light has a wavelength of range from 400-700nm, Violet light has a wavelength of 400nm whereas red light has a wavelength of 700nm.
• Violet light has a frequency of 7.5 x 1014  Hz whereas red light has a frequency of 4.3 x 1014Hz.
• The speed of light in a medium is constant.
• Light waves can be polarized.
• In a light wave, the electric and magnetic vectors oscillate.

## Sound Waves

Sound propagates through air or other mediums as a longitudinal wave, in which the mechanical vibration constituting the wave occurs along the direction of propagation of the wave. A sound wave consists of alternating compression and rarefactions or regions of high pressure and low pressure.

Sound like all waves, travels at a certain speed and has the properties of frequency and wavelength.  You can directly sense the frequency of a sound. Perception of frequency is referred to as pitch. The frequency of sound waves is the number of waves that pass a fixed point in a second. Frequency of sound waves varies between 20Hz and 20000Hz. Sounds with frequencies below 20Hz are referred to as infrasound whereas sounds with frequencies above 20000Hz are referred to as ultrasound.

Sound waves moves relatively at low velocity when compared to light waves. The velocity of sound waves is about 343 m/s at room temperature and atmospheric pressure. You can observe direct evidence of the speed of sound while watching a fireworks display. The flash of an explosion is seen well before its sound is heard, implying both that sound travels at a finite speed and that it is much slower than light.

### What You Need To Know About Light Waves

• Sound is only a wave. It does not show particular nature.
• Sound waves are longitudinal waves consisting of compressions and rarefactions.
• Sound waves require a material medium for propagation.
• Sound waves are of different frequencies giving notes of different pitches.
• Sound propagates by a chain reaction of density and pressure disturbances recreating each other.
• Sound waves do not travel far as their energy is dissipated easily.
• Sound waves moves relatively at low velocity when compared to light waves. The velocity of sound waves is about 343 m/s at room temperature and atmospheric pressure.
• The wavelength of sound frequencies audible to the human ear is approximately 17 m and 17 mm.
• Frequency of sound waves varies between 20Hz and 20000Hz. Sounds with frequencies below 20Hz are referred to as infrasound.
• The velocity of sound wave can change.
• Sound waves cannot be polarized.
• In sound waves, the particles of the medium actually oscillate.

## Difference Between Light And Sound Waves

 BASIS OF COMPARISON LIGHT WAVES SOUND WAVES Description Light wave can be considered to be made of waves as well as particles. Sound is only a wave. It does not show particular nature. Nature Light waves are electromagnetic or transverse waves consisting of varying electric and magnetic fields. Sound waves are longitudinal waves consisting of compressions and rarefactions. Medium Light waves do not require a material medium for propagation. The waves can travel in a vacuum. Sound waves require a material medium for propagation. Effect Light waves are of different frequencies, resulting in different colors. Sound waves are of different frequencies giving notes of different pitches. Propagation Light propagates by a chain reaction of electric and magnetic fields recreating each other. Sound propagates by a chain reaction of density and pressure disturbances recreating each other. Distance Of Travel Light waves can travel through a much greater distance. Sound waves do not travel far as their energy is dissipated easily. Velocity Light waves travels at much higher velocity as compared to sound waves. The velocity of light waves through a vacuum is 2.998 x 108 m/s. Sound waves moves relatively at low velocity when compared to light waves. The velocity of sound waves is about 343 m/s at room temperature and atmospheric pressure. Wavelength Visible light has a wavelength of range from 400-700nm, Violet light has a wavelength of 400nm whereas red light has a wavelength of 700nm. The wavelength of sound frequencies audible to the human ear is approximately 17 m and 17 mm. Frequency Violet light has a frequency of 7.5 x 1014  Hz whereas red light has a frequency of 4.3 x 1014Hz. Frequency of sound waves varies between 20Hz and 20000Hz. Sounds with frequencies below 20Hz are referred to as infrasound. Change In Velocity The speed of light in a medium is constant. The velocity of sound wave can change. Polarization Light waves can be polarized. Sound waves cannot be polarized. Oscillation of Matter In a light wave, the electric and magnetic vectors oscillate. In sound waves, the particles of the medium actually oscillate.
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