Notes on chapter 13 sounds
Answers
hope it help
Sound: Sound is a form of energy which creates sensation of hearing to our ears.
- This energy is in the form of waves.
- A medium is necessary for the propagation of sound.
- Study of sound is called as Acoustic
- Physics is a branch of science that deals with the study of sound.
Two types of sound waves:
i) Longitudinal waves: This waves are parallel to the propagation of the waves.
- In this waves, particle of medium oscillates about their central or mean positions.
ii) Transverse waves: This waves are perpendicular to the propagation of waves.
- In this waves, particles of medium oscillate up and down.
- Eg: when we drop stone in water; The particles of water oscillate up and down.
Some important concepts in sound:
- Wavelength: The wavelength of sound is denoted by geek letter lambda (λ).
- Frequency: Frequency of sound is indicated by nu (υ)
- Amplitude: It is the value of maximum pressure or density of sound wave.
- Compression: When the sound waves rise to chain of higher density then they are called as compression.
- Rarefaction: When the sound waves drop to the chain of lower density, then it is called as Rarefaction.
Velocity of sound:
Velocity of sound: The distance covered by a sound on the wave in unit time is called as velocity of sound wave.
Velocity of sound = υ λ
i.e. Velocity of sound = Wavelength / time period
V = λ / t
Hence, The velocity of sound wave = Wavelength * Frequency
Velocity of sound is different in different mediums. In solid states, sound travels faster as compare in liquid and air.
Velocity of sound in different mediums:
Aluminium - 5420 m/s
Nickel - 6040 m/s
Sea water - 1531 m/s
Ethanol - 1207 m/s
Hydrogen - 1284 m/s
Air - 346 m/s
Velocity of sound in gaseous medium depends upon on it's physical conditions like it's temperature, Density of gas and it's molecular mass.
- Velocity of sound is directly proportional to square root of temperature.
V α √T
- Velocity of sound is inversely proportional to the square root of density.
V α 1 / √p
- Velocity of sound is inversely proportional to the square root of Molecular mass
V α 1/M
Types of sounds:
i) Audible sound - Sounds which human ears can hear are called as Audible sounds. Or The sounds between frequency 20Hz to 20000Hz are called as Audible sounds.
- Frequency of this sounds is between 20Hz to 20000Hz (20KHz)
ii) Infrasonic sounds - Sounds with frequency less than 20Hz are called as Infrasonic sounds.
- Eg: Sounds produced by pendulum, Sound produced by earth before earthquake.
iii) Ultrasonic sounds - Sounds with frequency greater than 20000Hz are called as Ultrasonic sounds.
- Dog, Mouse, Bats have special type of ability to hear this sounds
Reflection of sound:
Like Light waves, Sound waves too get reflected. Sound waves also follow the all laws of reflection of light. Sound too needs a rough surface to get reflection of sound.
- Direction of incident sound wave and reflected sound wave make equal angles with perpendicular to the surface.
Echo
Echo is a repetition of the original sound because of reflection of some surface. At 22 Degree Celsius, the velocity of sound in air is 344 m/s, our brain retains a sound in 0.1 sec.
Thus, we can determine the minimum distance between the source and reflecting surface as given:
Distance = Speed * Time
= 344 m/s * 0.1
= 34.4 m
SONAR:
SONAR: Sound Navigation and Ranging.
SONAR is used to determine the icebergs, valleys, submarines, underwater hills. At one side of ship, transmitter is fitted, it transmits the ultrasonic sound and that sound touches the depth of sea and receiver receives the data and this data is properly interpreted for further information.
How sound is produced ?
Sound is produced through the vibrations in any medium. When there is a little bit vibration in any medium like Solid, liquid and gases, the particles of the medium vibrates and hence the sound is produces.
Different frequencies sound is produced at different conditions. A medium is necessary for the production of sound as well as propagation of sound.
How humans can hear the sound ?
We can hear the sounds because of our Ear. When the sound waves falls on the eardrum, it vibrates and this vibrations are converted into electrical signals, which travel towards the brain. And, brain can understand this electrical signals.
- Our brain receive a particular sound after 0.1 second when it was produced.
Our Ear have 3 main parts:
- Outer Ear (Collects the sound waves and passes through tube cavity to middle ear)
- Middle Ear ( Eardrum is present in this middle ear. It vibrates the waves provided by outer ear and convert it into electrical signals )
- Inner ear (Auditory nerve connects the inner ear to brain and connection between ear and brain is established)
Originally answered: https://brainly.in/question/932252