Nature of sound: Sound is a form of energy which produces a sensation of hearing in our ears. It is a vibration that propagates through a medium in the form of a mechanical wave. If there is no medium to vibrate then no sound is possible, sound cannot travel in a vaccum.
Reflection of sound: Sound reflects from a smooth surface in the same way the light does. The angle of incidence is equal to the angle of reflection.When a sound hits a hard surface, it reflects back to its source This reflection of the sound is called as echo. Sometimes, we hear multiple echoes from a source of the sound if the area is large and has multiple reflecting surfaces such as valleys and huge empty rooms. This phenomenon is known as reverbration.
Different sources produce different sounds: Sound produced by a guitar is different from produced by a drum. This is because the sound produced by different sources have different characteristics.Sound can be characterized by its frequency, wavelength and amplitude.
Speed of sound and light: The speed of sound in air is about 344 m/s at 22°C and 331 m/sec at 0°C and the speed of light in air is Thus, speed of light is very great as compared to the speed of sound. It is observed that in the rainy season, the flash of lighting is seen first and the sound of thunder is heard a little later, though both are produced at the same time in clouds. It is because of very high speed of light due to which we see the flash of lightning first and it is because of low speed of sound that the thunder is heard a little later.
Speed of sound in different media: Sound propagates through a medium at a finite speed. The medium can be a solid substance, a liquid or a gas. These are called material media. The speed of sound depends on the properties of medium through which it travels. The speed of sound in a medium depends on temperature of the medium. The speed of sound decreases when we go from solid to gaseous state. If temperature of the medium increases, then speed of sound also increases.
NOTE: SONIC BOOM: When the speed of any object exceeds the speed of sound, it is said to have supersonic speed. Many objects such as some aircrafts, bullets and rockets, etc, travel at supersonic speeds. When a sound producing source moves with a speed higher than that of sound, it produces shock waves in air, which carry a large amount of energy. The tremendous air pressure variations caused by the shock waves produce a loud burst of sound is known as sonic boom. It produces untolerable loud noise which causes pain in our ears. The shock waves produced by a supersonic aircraft have enough energy to shatter glass and can even damage buildings.
The frequency of a source 20 kHz. The frequencies of sound wave produced by it on water and air will be __________________ | |||
Right Option : A | |||
View Explanation |
You can predict the approaching train that is not in line of sight by | |||
Right Option : D | |||
View Explanation |
A person, pressing his ear on the railway tracks can hear an approaching train.This is possible due to: | |||
Right Option : C | |||
View Explanation |
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Usually we see institutes offering objective based learning which usually causes a lag behind in subjective examinations which is the pattern followed by schools. I think it is really a work of planning to make us students grab the advantages of modes of examination, Objective Subjective and Onli...
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Abhyas institute is one of the best coaching institute in the vicinity of Ambala Cantt area. The teachers of the institute are well experienced and very helpful in solving the problems of the students.The good thing of the institute is that it is providing extra classes for the students who are w...
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It was a good experience with Abhyas Academy. I even faced problems in starting but slowly and steadily overcomed. Especially reasoning classes helped me a lot.