Sound in One Shot | Physics - Class 8th | Umang | Physics Wallah

The speaker introduces a session about sound as energy and plans to cover different components of sound, including its transmission. They plan to discuss energy forms such as heat, chemical, and electrical energy, along with sound's role in communication and characteristics like amplitude, frequency, and time period. Examples will be used to explain concepts.

The speaker discusses how sound is produced through vibrating bodies and defines vibration. They explain that objects remain stable without disturbance but disturbances from external energy create system vibrations, which produce sound. An energy source like a chemical or an external force causes vibrations in particles, transferring energy through collisions.

The session explains that vibrating objects, including musical instruments, produce sound which we hear. The speaker uses examples like rubber bands and metal surfaces to illustrate vibrations and their role in producing sound. Vibrations are crucial in sound production, and this basic understanding helps explain why sound occurs.

The speaker describes that sound requires a medium to propagate. They use an analogy of ordering food and delivery to explain how air particles carry sound energy from a source to a receiver. Mediums like air, pressures within them, allow sound transmission. In a vacuum, sound cannot travel due to a lack of particles to transfer energy.

Mediums like air, liquid, and solids can transmit sound, with examples showing sound traveling through water. This explains underwater communication among aquatic animals. Speed of sound is fastest in solids due to closely packed particles, enabling efficient energy transmission compared to liquids and gases.

Details of the ear's structure are explained, showing how sound waves vibrate the eardrum and are transmitted to the brain. The process of sound entering the outer ear, vibrating the eardrum, traveling to the inner ear and being understood by the brain is outlined, explaining our ability to hear.

Amplitude, frequency, and time period as characteristics of sound are explained. Amplitude is the maximum displacement from a mean position, affecting loudness. Frequency relates to vibrations per second, influencing pitch. Examples help illustrate these concepts, explaining how they determine sound's perceptible qualities.

Differences between audible and inaudible sounds based on frequency range are discussed, with humans perceiving sounds within a certain frequency. Audible range is between 20Hz-20kHz, while sounds outside this are inaudible to humans but may be heard by animals like dogs or used in medical tools like ultrasounds.