Sound is mechanical energy that allows us to hear. The vibration of various things results in the production of sound. The sound wave propagates across the medium as compressions and rarefactions. Sound waves are waves that travel in a straight line. Before we get started, let us go over some fundamentals of chapter 12 class 9th science.
●A sound is a kind of energy that causes our ears to feel the sense of hearing.
●Sound propagation is the process through which sound is created by vibrating objects.
●The term "medium" refers to the matter or material that allows sound to be transferred via it. This substance might be solid,liquid, or gaseous. For sound transmission, air is the most often used medium.
●A wave is a disturbance that propagates in a medium when the particles of the medium cause the motion of nearby particles. They, in turn, cause others to move in a particular manner. The disturbance is what causes the sound to move ahead, rather than the particles themselves. This is what occurs during the transmission of sound across a medium, and as a result, sound may be represented as a wave. Mechanical waves are sound waves that are characterised by the movement of particles in a medium.
●The forward motion of a vibrating item causes the air in front of it to be pushed and compressed, resulting in the formation of an area of high pressure. This area is referred to as a compression (C). This compression begins to dissipate away from the item that is vibrating. A zone of low pressure is created when a vibrating item goes backwards; this is referred to as rarefaction (R).
●Due to the fast movement of the item back and forth, a sequence of compressions and rarefactions are formed in the surrounding air. These are responsible for creating the sound wave that travels through the medium.
●The frequency of sound waves is defined as the number of oscillations that occur in a given period of time. Frequency is also defined as the number of peaks and troughs per unit of time in a certain period of time. It is denoted by the symbol ‘v’, and its SI unit is the Hertz (Hz).
●The time period of an oscillation is defined as the amount of time it takes to complete one oscillation. Its unit is the second, and it is denoted by the letter T.
●The following is the relationship between frequency and time period: v = 1/T
●The amplitude of a wave is defined as the size of the largest disturbance in the medium on each side of the mean value on either side of the wave's axis. The letter A is often used to represent it in writing. Its measurement unit is the metre.
●Whether a sound is softer or louder depends on the amplitude of the sound. If the amplitude is less, the sound will be softer, and if it is bigger, the sound will be louder.
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