Sound NCERT Solutions - Class 8 Science
Q1: What are the physical factors that affect sound propagation?
A1: Physical factors that affect the propagation of sound are as mentioned below:
Atmospheric Turbulence: in case of any kind of turbulence in the atmosphere in which the sound wave is travelling is turbulent, then the sound waves will scatter due to velocity fluctuations that occur in -the medium.
Wind Gradient: Sound propagating in the direction of the wind would bend downwards. The sound propagating against the direction of wind will bend upwards.
Temperature Gradient: Sound waves travel faster in a warm atmosphere near the surface of the earth. It is because of an upward refraction of sound waves. In case of any decrease in temperature at higher altitudes, the refraction will be downwards.
Q2: Is it possible for Sound to Travel in Space?
A2: Sound can only propagate in a medium. It is impossible for sound to travel without a medium. This is due to the fact that there are no molecules that can be compressed and expanded in vacuum. Our voice is produced by the vibration of strings known as the vocal cords that are present inside Adam’s apple. When you make a sound, its vibration travels through the air. When it reaches your brain through your ears, it is interpreted by the brain as sound waves and then converted to an appropriate message for us to identify the sound. In this scenario, the propagation of sound takes place through the air medium. This does not therefore occur in space due the lack of a medium for the sound to propagate. Therefore sound cannot travel in space.
Q3: What are the sub-topics covered in chapter 13 sound?
A3: Subtopics of NCERT Solutions for class 8 Science Chapter 13 Sound
13.1 The sound is Produced by a Vibrating Body
13.2 Sound Produced by Humans
13.3 Sound Needs a Medium of Propagation
13.4 We Hear Sound through Our Ears
13.5 Amplitude, Time Period and Frequency of a Vibration
13.6 Audible and Inaudible Sounds
13.7 Noise and Music
13.8 Noise Pollution.
All the above subtopics will have various exercises related to them. These exercises have questions which are aimed at improving the conceptual understanding of the chapters. These questions are extremely important from an exam point of view as many questions will either be picked directly from the exercises or will be very similar to them. Therefore students must ensure that they solve all the problems in the exercise. To make the processing of answering the exercises questions easier, Vedantu provides NCERT Solutions for students. These solutions have accurate well written answers for all the exercise questions. These answers are written by subject matter experts making it extremely reliable and one of the most sought after study materials by the students.
Q4: Give a few important points that students learn in this chapter.
A4: A few important points that students learn in this chapter are mentioned below:
The vibration of the vocal cords produces sound in humans
The eardrum senses these vibrations of sound,and then sends them to the brain. This process is called hearing.
The frequency of sound is expressed in hertz (Hz)
Sounds that are unpleasant to the ear are called noise.
Noise pollution should be reduced as much as possible
Increasing the plantation of trees will help reduce noise pollution.
Sound can only travel through a medium (gas, liquid or solid). It cannot travel in a vacuum.
Higher the frequency of vibration, the higher is the pitch, and shriller is the sound.
Atmospheric turbulence, wind gradient and temperature gradient are the factors that affect the propagation of sound waves.