Sound (ध्वनि) Ch(11) Practice Quiz in Hindi Part – 1 || Class 9 Science Practice Quizzes in English Posted on February 28, 2025February 28, 2025 by Anshul Gupta0% 0 votes, 0 avg 1 Sound (ध्वनि) Ch(11)Practice Quiz in Hindi Part – 1 || Class 9 Science Practice Quizzes in English 1 / 201. The time taken for one complete oscillation is called: A. Amplitude B. Frequency C. Time period D. Wavelength Explanation: Time period is measured in seconds. 2 / 202. The reflection of sound follows: A. Only the law of refraction B. No specific laws C. The same laws as light reflection D. Different laws than light reflection Explanation: The angle of incidence equals the angle of reflection, and the incident sound wave, reflected sound wave, and the normal to the surface all lie in the same plane. 3 / 203. The law of conservation of energy states that: A. Energy cannot be created or destroyed, only transformed B. Energy can be created C. Energy can be destroyed D. Energy is always constant Explanation: The law of conservation of energy states that energy cannot be created or destroyed, but it can be converted from one form to another. 4 / 204. The speed of sound in air at 0°C is approximately: A. 1531 m/s B. 331 m/s C. 344 m/s D. 5950 m/s Explanation: The speed of sound in air increases with temperature. 5 / 205. Sound waves are characterized by: A. The motion of particles perpendicular to the direction of wave propagation B. The absence of particle motion C. The motion of particles parallel to the direction of wave propagation D. The transfer of particles through the medium Explanation: This type of wave is called a longitudinal wave. 6 / 206. A region of high pressure in a sound wave is called: A. Trough B. Compression C. Crest D. Rarefaction Explanation: Compression is formed when the vibrating object pushes the air particles closer together. 7 / 207. The speed of sound is: A. Constant in all media B. Dependent on the properties of the medium C. Always faster in solids than in liquids D. Not affected by temperature Explanation: The speed of sound is generally higher in denser materials. 8 / 208. Sound is a form of: A. Light energy B. Potential energy C. Kinetic energy D. Mechanical energy Explanation: Sound is produced by vibrations, which involve the movement of particles. This movement is a form of mechanical energy. 9 / 209. The distance between two consecutive compressions or rarefactions is called: A. Amplitude B. Wavelength C. Time period D. Frequency Explanation: Wavelength is the distance over which the wave’s shape repeats. 10 / 2010. An echo is: A. The persistence of sound due to repeated reflections B. The absorption of sound waves C. The bending of sound waves D. The repetition of a sound due to reflection from a surface Explanation: An echo is heard when the reflected sound wave reaches the listener’s ear after the original sound wave has ended. 11 / 2011. A region of low pressure in a sound wave is called: A. Crest B. Trough C. Compression D. Rarefaction Explanation: Rarefaction is formed when the vibrating object moves backward, creating more space between the air particles. 12 / 2012. Megaphones and horns are designed to: A. Send sound in a particular direction B. Reduce the speed of sound C. Spread sound in all directions D. Increase the frequency of sound Explanation: They use multiple reflections to focus the sound waves. 13 / 2013. The number of oscillations per unit time is called: A. Time period B. Frequency C. Amplitude D. Wavelength Explanation: Frequency is measured in Hertz (Hz). 14 / 2014. The minimum distance of the obstacle from the source of sound for hearing a distinct echo is: A. Dependent on the speed of sound only B. 17.2 m C. 8.6 m D. 34.4 m Explanation: This distance is calculated based on the speed of sound in air and the time required to hear a distinct echo. 15 / 2015. The substance through which sound is transmitted is called a: A. Insulator B. Vacuum C. Conductor D. Medium Explanation: A medium can be a solid, liquid, or gas. Sound cannot travel through a vacuum. 16 / 2016. When an object vibrates, it causes: A. The particles of the medium to vibrate in a chain reaction B. The speed of sound to decrease C. The particles of the medium to travel all the way to the listener D. The medium to remain stationary Explanation: The vibration of one particle causes the adjacent particles to vibrate, transmitting the sound wave. 17 / 2017. Sound is produced by: A. Light waves B. Heat energy C. Vibrating objects D. Stationary objects Explanation: Vibrations create disturbances in the surrounding medium, which propagate as sound waves. 18 / 2018. To hear a distinct echo, the time interval between the original sound and the reflected sound should be at least: A. 10 s B. 1 s C. 0.1 s D. 0.01 s Explanation: This is because the sensation of sound persists in our brain for about 0.1 s. 19 / 2019. A stethoscope is used for: A. Listening to sounds produced within the body B. Reducing reverberation C. Amplifying sound waves D. Measuring the speed of sound Explanation: It uses multiple reflections to transmit the sound of the patient’s heartbeat to the doctor’s ears. 20 / 2020. Reverberation is: A. The bending of sound waves B. The persistence of sound due to repeated reflections C. The absorption of sound waves D. The repetition of a sound due to reflection from a surface Explanation: Reverberation can be reduced by using sound-absorbing materials on the walls and ceilings of a room. 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