Welcome to the 10th Class Physics Notes for Unit 11 – Sound! In this comprehensive set of notes, we will explore the fascinating world of sound and its various properties and characteristics. Sound is an essential aspect of our daily lives, influencing communication, music, and even our understanding of the world around us. Through these notes, we will delve into the nature of sound waves, their propagation, and how they interact with different mediums. From understanding the basics of sound production to exploring the intricacies of resonance and sound intensity, this unit will provide you with a solid foundation in the physics of sound. So, let’s embark on this exciting journey to unravel the mysteries of sound and its role in shaping our auditory experiences.
10th Physics Unit 11 Long Question Notes
10th Physics Unit 11 MCQ’s Long Question Notes
10th Physics Unit 11 Numerical Notes
- 10th Class Pak Study Textbook
- 9th and 10th Class General Science Textbook
- Chapter No. 9 Notes 10th Chemistry
- Biology 10th Class Past Papers
- English Past Papers of 10th Class
10th Physics Unit 11 Short Question Notes
What produces waves in any medium?
Answer: Vibrations of objects in any medium produce waves.
Give an example of a vibrating body that produces sound waves.
Answer: A guitar produces sound due to the vibrations of its strings.
How do doctors use a stethoscope to hear sound waves?
Answer: Doctors use a stethoscope to listen to sound waves produced by the human heart and other organs like lungs.
What type of waves are sound waves?
Answer: Sound waves are longitudinal waves.
What happens when a tuning fork is struck against a rubber hammer?
Answer: The tuning fork begins to vibrate, producing sound waves.
In what medium do sound waves require for their propagation?
Answer: Sound waves require air (or any material medium) for their propagation.
What is the longitudinal nature of sound waves?
Answer: Sound waves propagate through the air in the direction of oscillating air molecules, creating compressions and rarefactions.
How can you distinguish different sounds based on their characteristics?
Answer: Different sounds can be distinguished based on characteristics like loudness, pitch, and quality.
What is the factor that determines the loudness of sound?
Answer: The loudness of sound is determined by the amplitude of the vibrating body.
How does the distance from the vibrating body affect the loudness of sound?
Answer: The loudness of sound decreases as the distance from the vibrating body increases.
What is pitch in sound?
Pitch is the characteristic of sound that allows us to distinguish between a shrill and a grave sound. It depends on the frequency, where higher pitch corresponds to higher frequency, and vice versa.
Why is the voice of women more shrill than that of men?
The voice of women is more shrill than that of men because the frequency of their voice is higher. Pitch is directly related to frequency, so higher frequency results in a higher-pitched sound.
What is quality in sound?
Quality is the characteristic of sound that allows us to distinguish between two sounds of the same loudness and pitch. It is determined by the difference in waveforms of the sounds and can be recognized by the human ear.
What is intensity in sound?
Intensity is the measure of the energy transferred by sound waves from the sounding body to the listener. It depends on the amplitude of the sound wave and is measured in watts per square meter (W/m²).
How is loudness related to sound intensity?
Loudness (L) of a sound is directly proportional to the logarithm of its intensity (I). Mathematically, L = K log I, where K is a constant of proportionality.
What is the unit used to measure the intensity level of sound?
The unit used to measure the intensity level of sound is the decibel (dB).
How is the intensity level of sound calculated?
The intensity level (IL) of sound is calculated using the formula: IL = 10 log (I/I₀), where I is the intensity of the sound and I₀ is the faintest audible sound intensity (reference intensity).
What causes an echo of sound?
An echo of sound is caused by the reflection of sound waves from a surface. When sound waves encounter a reflecting surface, they bounce back into the first medium, creating the sensation of an echo.
What is the minimum distance required to hear a distinct echo?
To hear a distinct echo, the minimum distance required between the source of sound and the reflecting surface is half the total distance covered by sound in 0.1 seconds. For example, in air at normal temperature, this distance is approximately 17 meters.
What are elephants’ large ears used for?
Answer: Elephants use their large ears to detect low-frequency sound waves and communicate with each other, even when separated by long distances.
What is the loudest animal sound ever recorded, and which animal produces it?
Answer: The loudest animal sound ever recorded is a blue whale’s 180 dB rumble.
Why can whales communicate over long distances?
Answer: Whales can communicate over long distances because sound waves travel five times faster in water than in air, allowing their calls to propagate over hundreds and possibly thousands of kilometers.
How can you calculate the frequency of a sound wave?
Answer: The frequency of a sound wave can be calculated using the formula v = f λ, where v is the speed of sound, f is the frequency, and λ is the wavelength of the sound wave.
How can you measure the speed of sound using the echo method?
Answer: To measure the speed of sound using the echo method, clap your hands in front of a flat wall at a known distance, measure the time interval between the clap and the echo, and then use the formula S = vt to calculate the speed of sound.
What is noise pollution, and what are its effects?
Answer: Noise pollution is an undesirable sound that can be harmful to human and other species. It can cause conditions such as hearing loss, sleep disturbances, aggression, hypertension, and high stress levels.
What are the main sources of noise pollution?
Answer: The main sources of noise pollution are transportation equipment, heavy machinery, loud vehicle horns, hooters, and alarms.
What is the safe level of noise, and how is it measured?
Answer: The safe level of noise is usually recommended to be 85-90 dB over an eight-hour workday. It is measured using decibels (dB) as a unit of sound intensity.
How can noise pollution be reduced to an acceptable level?
Answer: Noise pollution can be reduced by replacing noisy machinery with environment-friendly equipment, using sound-reducing barriers, or providing hearing protection devices.
Why was the speed of sound in air first accurately measured in 1738?
Answer: The speed of sound in air was first accurately measured in 1738 by members of the French Academy using two cannons set up approximately 29 km apart. By measuring the time interval between the flash of a cannon and the sound of the “boom,” they calculated the speed of sound.
What is the technique used to absorb undesirable sounds by soft and porous surfaces?
Answer: Acoustic protection.
How does the reflection of sound vary depending on the surface?
Answer: Reflection of sound is more prominent on rigid and smooth surfaces, and less on soft and irregular surfaces.
What materials can absorb large amounts of sound energy, reducing noise pollution?
Answer: Soft and porous materials such as draperies and rugs.
What is the range of frequencies that a normal human ear can hear, known as?
Answer: The audible frequency range, which lies between 20Hz and 20,000 Hz.
What are sounds of frequency higher than 20,000 Hz called, and what are their uses?
Answer: They are called ultrasound or ultrasonics, and they are used in medical and technical fields for various applications such as medical imaging, detecting small objects, and locating underwater depths.
How do bats “see” in the dark, and what technology allows humans to “see” using sound waves?
Answer: Bats and dolphins have the ability to “see” using sound waves (echolocation). Research has developed technology that enables humans to “see” using sound waves, like in SONAR systems.
What is the purpose of placing reflective surfaces behind the stage in a theater hall?
Answer: Reflective surfaces are placed behind the stage to direct sound towards the audience.
What is the advantage of using curved ceilings and sound boards in halls and theaters?
Answer: Curved ceilings and sound boards help evenly distribute reflected sound across the hall, improving acoustics.
How are ultrasonic waves used in medical applications?
Answer: Ultrasonic waves are used for diagnosing diseases and internal organ imaging, such as in ultrasound tests.
How is SONAR (sound navigation and ranging) used to locate objects underwater?
Answer: SONAR sends sound waves from a transmitter, and a receiver collects the reflected sound. By calculating the time-lapse and knowing the speed of sound in water, the distance of the object from the ocean surface can be estimated.