Describe with the help of a diagram, how compressions and rarefactions are produced in air near a source of sound.
Solution and Explanation
Compression:
This refers to the section of the medium where particles move closer than their normal separation distance.
Rarefaction:
This pertains to the portion of the medium where particles move apart to distances greater than their normal separation distance.
Explanation:
When a tuning fork vibrates, its prong compresses the air particles immediately in front of it. As a compression wave propagates horizontally through the air, the air particles undergo periodic motion along the horizontal direction.
In a longitudinal wave, if the particles of the medium vibrate horizontally, the disturbance also travels horizontally. Moreover, this wave travels in the form of compressions and rarefactions.
The wavelength is the distance between the centers of two consecutive compressions or rarefactions.
The velocity of the longitudinal wave is determined by:
\(V=fλ\)
Where \(f\) is the frequency and \(λ\) is the wavelength,
Top Questions on Production of Sound
- What is sound and how is it produced?
- CBSE Class IX
- Science
- Production of Sound
Questions Asked in CBSE Class IX exam
- The author speaks both of people who were very aware of the differences among them and those who tried to bridge these differences. Can you identify such people in the text?
- CBSE Class IX
- My childhood
- Explain what the reasons for the following are.
(i) Einstein leaving the school in Munich for good.
(ii) Einstein wanting to study in Switzerland rather than in Munich.
(iii) Einstein seeing in Mileva an ally.
(iv) What do these tell you about Einstein?- CBSE Class IX
- A truly beautiful mind
- (i) The kind of person the doctor is (money, possessions)
(ii) The kind of person he wants to be (appearance, ambition)- CBSE Class IX
- The snake and the mirror
In Fig. 9.26, A, B, C and D are four points on a circle. AC and BD intersect at a point E such that ∠ BEC = 130° and ∠ ECD = 20°. Find ∠ BAC.
- CBSE Class IX
- Angle Subtended by an Arc of a Circle
- Name the two temples the author visited in Kathmandu.
- CBSE Class IX
- Kathmandu
Concepts Used:
Sound
Sound is a vibration that propagates the mechanical wave of displacement and pressure, through a medium can be of any matter. In other words, the sound is the thin line between Music sound and Noise.
Types of Sounds:
Sound can be divided into two types depending on its frequency. The following are:-
Infrasonic Waves:
- Infrasonic waves have a frequency lower than 20 Hz. Since it is below the human hearing range, it is inaudible to humans.
- However, several other living organisms use these waves to communicate, whales, sharks, elephants, hippopotamus, etc. these waves are also used in the scientific field, it is used to study upcoming earthquakes, volcanic eruptions, human heart rates, rock formation stages, etc.
Ultrasonic waves:
- Ultrasonic waves have a frequency higher than 20 kHz. Since it is above the human hearing range, it is inaudible to humans.
- These waves are used in the scientific field, it is used to study human heart rates, to take sonograms, navigation of directions, imaging things, uniform sample mixing, communication, testing of samples, etc.