What is Sound?
Sound may be defined as the physical cause which enables us to have the sensation of hearing.
Sound is a mechanical wave motion, in an elastic medium moving at a speed of 340 m/s.Sound is made up of the vibrations of atoms or molecules passing through a substance, and so without atoms or molecules (i.e. in a vacuum) it cannot travel.
How this Mechanical wave motion is produced and reaches the ear and what happens to the medium through which it travels?
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Thus, sound waves are mechanical waves. when a strings of a violin or sitar is plucked, it is clearly seen to vibrate. This produces mechanical disturbance in the medium by displacing the particles of the medium. This explains the mechanical nature of sound waves.
Sound is a wave motion:
Points to remember:
Both sound and light are associated with wave motion.
Sound may be defined as the physical cause which enables us to have the sensation of hearing.
Sound is a mechanical wave motion, in an elastic medium moving at a speed of 340 m/s.Sound is made up of the vibrations of atoms or molecules passing through a substance, and so without atoms or molecules (i.e. in a vacuum) it cannot travel.
Properties of Sound Waves:
1. Sound waves are longitudinal mechanical waves.
2. Some material medium is required for the propagation of sound waves. Therefore, they cannot travel through vacuum.
3. There is always a transfer of energy in the direction of propagation of the sound waves.
4. Sound waves exhibit the phenomenon of reflection, refraction and interference.
5. The velocity of sound is greater in solids, lesser in liquids and least in gases.
How this Mechanical wave motion is produced and reaches the ear and what happens to the medium through which it travels?
The source of sound is always found to be in a state of vibration. These vibrations may be so small or rapid as not to be easily seen or detected. A ringing bell, the head of drum, the string of sitar, a tuning fork etc. are always found to be in a state of vibration when they are producing sound. Humans voice originates from the vibrations of the vocal chords and the organ pipie produces the sound due to the vibrating air columns.
To demonstrate the existence of vibrations in sounding body, strike a tuning fork against a rubber pad. Touch one of the prongs of a tuning fork with your hand. The sensation of vibrations will be felt.
The vibrating tuning fork: sets off series of periodic compressions & rarefactions (longitudinal waves). The frequency of longitudinal waves is equal to the vibrating frequency (natural frequency) of the tuning fork.
When a tuning fork is struck, it vibrates back and forth at its natural frequency.
natural frequency- frequency at which an elastic object once energized will vibrate, a minimum amount of Energy is needed to continue vibrating at that frequency.
Thus, sound waves are mechanical waves. when a strings of a violin or sitar is plucked, it is clearly seen to vibrate. This produces mechanical disturbance in the medium by displacing the particles of the medium. This explains the mechanical nature of sound waves.
Sound is a wave motion:
Sound produced by a vibrating body cannot be heard until it reaches the ear of the listener. When sound is produced by a body, the body is in state of rapid vibrations. The energy of the vibrating body is transferred to the particles of the surrounding medium (air). This makes the particles of the medium to vibrate.
As a result, the disturbance is handed over from particle to particle of the medium. This disturbance (wave) travels in the form of compressions and rarefactions and on reaching the membrane of the ear sets it into vibrations, producing the sensation of hearing. It follows therefore, that sound is wave motion.
Both sound and light are associated with wave motion.
Light Waves are electro-magnetic waves propagating in free space at a very high speed of 3.00 x 108 m/s.On the other hand, sound is a mechanical wave motion, in an elastic medium moving at a speed of 340 m/s.
Sound waves passing through the air cause air molecules to move back and forth parallel to the direction that the wave is traveling. This back and forth motion of the air molecules results in alternating regions of high pressure and low pressure. A region of high pressure is called a "compression," and a region of low pressure is called a "rarefaction."
The time it takes for a region to be compressed, and then rarefied, is called the period (T). It is measured in seconds.
The number of times that a region is compressed in one second is called the frequency (f). Frequency is measured in Hertz (Hz), which is the inverse of a second.
The wavelength (λ) is the physical distance from one point of compression to the next, and it is measured in meters. Using a microphone, we can determine the frequency of a sound by graphing air pressure versus time and observing the pattern set up by the constantly changing volume. This pattern is called a waveform.
Light Waves: Light is that agency which produce in us the sensation of sight. It itself is not visible but is necessary in seeing other things.
Like all other waves, light waves also carry energy with them. The transfer of energy by light waves is in the form of radiations. Light waves are also known as electromagnetic transverse waves.
Velocity of light in vacuum is approximately 3 x 108 m/s or 186282 miles per second.
Luminous Intensity of light is measured in Candela (Cd) and Luminous energy in Lumen second (lm s) in S.I units.
Light has a dual nature i.e., sometimes it has particle nature to explain phenomenas like Photoelectric effect, Compton effect, Raman effect etc. and sometimes it behaves like wave to explain the phenomenas like reflection of light, interference, diffraction and polarization of light, etc.
Courtesy: scienceprojectideasforkids
animatedscience.co.uk
w3.shorecrest.org
appstate.edu
Sound waves passing through the air cause air molecules to move back and forth parallel to the direction that the wave is traveling. This back and forth motion of the air molecules results in alternating regions of high pressure and low pressure. A region of high pressure is called a "compression," and a region of low pressure is called a "rarefaction."
The time it takes for a region to be compressed, and then rarefied, is called the period (T). It is measured in seconds.
The number of times that a region is compressed in one second is called the frequency (f). Frequency is measured in Hertz (Hz), which is the inverse of a second.
The wavelength (λ) is the physical distance from one point of compression to the next, and it is measured in meters. Using a microphone, we can determine the frequency of a sound by graphing air pressure versus time and observing the pattern set up by the constantly changing volume. This pattern is called a waveform.
Light Waves: Light is that agency which produce in us the sensation of sight. It itself is not visible but is necessary in seeing other things.
Like all other waves, light waves also carry energy with them. The transfer of energy by light waves is in the form of radiations. Light waves are also known as electromagnetic transverse waves.
Velocity of light in vacuum is approximately 3 x 108 m/s or 186282 miles per second.
Luminous Intensity of light is measured in Candela (Cd) and Luminous energy in Lumen second (lm s) in S.I units.
Light has a dual nature i.e., sometimes it has particle nature to explain phenomenas like Photoelectric effect, Compton effect, Raman effect etc. and sometimes it behaves like wave to explain the phenomenas like reflection of light, interference, diffraction and polarization of light, etc.
Light sometimes refers to electromagnetic radiations of any wavelength visible or not. Visible region for normal human vision has wavelength ranging from 3800 Å to 7600 Å [1 Å = 1.0 × 10-10 meters].
Courtesy: scienceprojectideasforkids
animatedscience.co.uk
w3.shorecrest.org
appstate.edu
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