Skip to main content


Think like a proton and stay positive

Sound waves are mechanical longitudinal waves and require a medium for their propagation.

Sound cannot propagate through vacuum.
When it propagates, speed and wavelength changes but the frequency remain constant.
It is of three types
Infrasonic waves – (0 to 20 Hz)
Audible waves – (20 to 20,000 Hz)
Ultrasonic waves – (>20,000 Hz)

Properties of Sound Wave


  • The bouncing back of sound when it strikes a hard surface, is called reflection of sound.
  • The laws of reflection of light are also obeyed during reflection of sound.
  • The working of megaphone, soundboards, and ear trumpets are based on the reflection of sound.
  • The repetition of sound due to reflection of sound waves, is called an echo.

  • The minimum distance from a sound-reflecting surface to hear an echo is nearly 17 m.

  • The persistence of hearing on the human ear is 1/10th of a second.

  • Soundproof rooms are made of two layers of walls having a vacuum between them. 


  • It arises due to multiple reflections of sound.
  • While designing an auditorium for speech or musical concerts, one has to take proper care for the absorption and reflection of sound.
  • Time taken by reverberant sound to decrease its intensity by a factor of 106 is called reverberation time.


When a sound wave moves from one mechanical medium to another mechanical medium, it shows deviation from the original path of the incident wave. The phenomenon is called refraction. It is due to the difference in speed of sound in media.


When sound waves originated by a vibrating source, they spread in the medium and if the medium is homogeneous, this leads to a bending of sound waves around the edges. Which is known as diffraction.
The sound waves diffracted broadly, therefore, one can easily hear the voice of another person.

Doppler’s Effect

The apparent change in the frequency of source due to relative motion between the source and the observer is called Doppler’s effect.

Applications of Doppler’s Effect

1. The measurement of Doppler shift (based on Doppler’s effect) has been        used by police to check over speeding of vehicles.
2. By Astrophysicists to measure the velocities of planets and stars.
3. At airports to guide the aircraft.
4. To study the heart and blood flow in different parts of the body.


  • SONAR stands for Sound Navigation and Ranging. It is used to measure the depth of a sea, to locate the enemy submarines and shipwrecks.
  • The transmitter of a sonar produces pulses of ultrasonic sound waves of the frequency of about 50000 Hz. The reflected sound waves are received by the receiver.


We are able to hear with the help of an extremely sensitive organ of our body called the ear.

There are three parts of the human ear
  • The outer ear is called pinna. It collects the sound from the surroundings.
  • The middle ear transmits the amplified pressure variations received from the sound wave to the inner ear.
  • In the inner ear, the pressure variations are turned into electrical signals by the cochlea. These electrical signals are sent to the brain via the auditory nerve and the brain interprets them as sound.




  1. Replies
    1. Thanks for the appreciation
      Come again to visit for interesting structured content

  2. When writing about your interests try and show how they can have some relevance to the job and make sure that you are able to talk about them enthusiastically for at least 5 minutes. essay writing

  3. It's very difficult to stumble upon the right essay service for your college needs. That's why the best essay writing service reddit was created for troubled college students.

  4. You can find these online or you might have some at home that you've received in the mail. If it's online, make sure that you print it out so you have a physical copy. Direct Response Copywriting


Post a Comment

Popular Posts


BABUR Descendent of Timur (from his father side) and Genghis khan (from his mother side)It is said that he was invited in India by Daulat Khan Lodi and Alam kha lodiHe laid the foundation of the Mughal empire by defeating Ibrahim Lodi in the first battle of Panipat on 21, April 1526.In 1527, he defeated Rana Sanga of Mewar at Khanwa.In 1528, he defeated Medini Rai of Chaneri at Chanderi.In 1529, he defeated Muhammad Lodhi (uncle of Ibrahim Lodhi) at Ghaghra.In 1530, he died at Agra. His tomb is at Lahore. The tomb of only two Mughal emperors are outside India i.e. Babur & Bahadur Shah ZafarHe was the first to use gunpowder & artillery in India.Two gun masters Mustafa & Ustad Ali were in his armyHe wrote his autobiography Tuzuk-i-Baburi in Turki.Tuzuk-i-Baburi was translated in Persian (named Baburnama) by Abdur Rahim Khan-e-khana & in English by Madan Bebridge.He compiled two anthologies of poems, Diwan (in Turki) & Mubaiyan (in Persian). He also wrote Risal-i-Usaz …



The only way to learn MATHEMATICS is to do MATHEMATICS

Trigonometry, the branch of mathematics concerned with specific functions of angles and their application to calculations. There are six functions of an angle commonly used in trigonometry. Their names and abbreviations  sine (sin), cosine (cos), tangent (tan), cotangent (cot), secant (sec), and cosecant (csc). The word trigonometry comes from the Greek words trigonon (“triangle”) and metron (“tomeasure”). The first use of the idea of ‘sine’ in the way we use it today was in the work Aryabhatiyam by Aryabhata, in A.D. 500. Aryabhata used the word ardha-jya for the half-chord, which was shortened to jya or jiva in due course. When the Aryabhatiyamwas translated into Arabic, the word jiva was retained as it is. The word jiva was translated into sinus, which means curve, when the Arabic version was translated into Latin. Soon the word sinus, also used as sine, became common in mathematical texts throughout Europe. An English Professor of…


One-liner knowledgeable modern Indian history incidents, that rapidly boost your memory

1905 --> Partition of Bengal by Lord Curzon, swadeshi movement, Rakhi diwas
                 (by Rabindranath Tagore)
1906 --> Muslim league was founded by Aga Khan, Salim Ullah in Dhaka
1907 --> Congress split, Tata steel established
1908 --> Swadeshi stopped, first-time Gandhiji went to jail
1909 --> Morley-Minto reforms
1911 --> Delhi darbar, Bengal partition revoked
1912 --> 23 December, Delhi became capital of British empire in India
1913 --> Gadar party, Rabindranath Tagore won Nobel prize
1914 --> World war I started
1915 --> 9, January 1915 Gandhiji Returned to India, NRI Day is celebrated on thisday every year
1916 --> Lucknow pact, Home rule league, Gandhiji established Sabarmati Ashram
1917 --> Champaran satyagraha
1918 --> Ahmedabad Mill Strike, Kheda Satyagragh, Montague Chelmsford reform
1919 --> Rowlett Act (10 march), Jaliawalah Bagh massacre (13 April 191…