Question

class 9 sound chapter important questions

Answer 1

sonar, wavelength, and numericals.

Answer 2

The pattern in which the Question Paper is set is quite different from the style in which the course structure is actually defined. Consider the below mentioned terms/questions at the time of preparation.

Sound and its importance for us. Characters of a sound waveMechanical wave and its propertyWhat type of energy sound is?Definitions of longitudinal and transverse wavesDefine wave frontSound is a mechanical wave. JustifyCan sound wave travel in vacuum?Examples of electromagnetic wavesFactors affecting the speed of soundSpeed of sound in solid, liquid, and gas (very important)Audible range for humans and other animalsPropagation of sound. Can sound propagate through vacuum?How does the sound produced by a vibrating object in a medium reach your ear?Why sound needs a medium to travel?What type of wave is represented by density-distance graph?Transverse wave cannot travel through gases or air. Why?Definition of wave length, frequency, time period, amplitude, and oscillationWhat is wave number?Relation between speed, frequency, and wave lengthConcept and formation of compressions (C) and rarefactions (R)What do you mean by quality of sound?Which wave property determines

           (a) Loudness (b) Pitch

A person is listening to a tone of 500 Hz sitting at a distance of 450 m from the source of the sound. What is the time interval between successive compressions from the source?What is intensity of sound? Intensity and loudness are same or different. ExplainA sound wave has frequency of 2 KHz and wavelength 35 cm. How long will it take to travel 1.5 KmIs there any difference between reflection of sound and reflection of light?What is echo? Echo is related to reflection or refraction?Numerical based on echo.(Very important)An echo returned in 3 s. What is the distance of the reflecting surface from the source, given that the speed of sound is 342 m s–1?Reverberation and its applicationsUses of multiple reflections of soundCeilings of cinema halls and conference halls are always curved. Why?Frequency range of ultrasound and its uses (Important)Expand SONAR and mention its usesA ship sends out ultrasound that returns from the seabed and is detected after 3.42 s. If the speed of ultrasound through seawater is 1531 m/s, what is the distance of the seabed from the ship?What type of sound is emitted by prey?Neat and clean diagram of human ear with all audible parts.Functions of all the parts given below:

          1. Pinna

          2. Auditory canal

          3. Tympanic membrane

          4. Cochlea

Name the three bones found in the middle ear

Important Questions are as below:

Q. What happens when a wave travels through a medium

1) Particles are transferred from one place to another

2) Energy is transferred in a periodic manner

3) Energy is transferred at a constant speed

4) None of the above statements is applicable

Q. Bats detect the obstacles in their path by receiving the reflected

1) Ultrasonic waves

2) Electro-magnetic waves

3) Radio waves

4) Infrasonic waves

Q. The physical quantity, which oscillates in most waves, is

1) Wave length

2) Energy

3) Amplitude

4) Mass

Q. The distance between a compression and the next rarefaction of a longitudinal wave is __________.

1) λ/8

2) 2l

3) λ/4

4) λ/2

Q. When is echo heard?

1) If the time interval between original sound and reflected sound is more than 1/10 sec.

2) If the time interval between original sound and reflected sound is less than 1/20 sec.

3) If the time interval between original sound and reflected sound is less than 1/10 sec.

4) If the time interval between original sound and reflected sound 1/20 sec.

Q. What type of sound wave can propagate in solids?

1) Longitudinal only

2) Transverse only

3) Either longitudinal or transverse

4) Non mechanical wave only