Question Pool Wave Motion

# Wave Motion - SAMAGRA Question Pool & Answers | Class 9 English Medium

Kerala Syllabus SAMAGRA SCERT SAMAGRA Question Pool for Class 9 English Medium Physics Wave Motion

Qn 1.

The graph shown below gives the displacement and the distance travelled by a wave in 2 seconds

a. complete the table using the graph shown below

 Charecteristics of the wave measured value Amplitude 2 cm wavelegth .............(i).............. Frequency .............(ii)............

b. What is the velocity of the wave given above

i.10m

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Qn 2.

Examine the word pair given below.

i. : Frequency

ii. ƛxf : ...............

a. Write down the relationship in the first pair of words.

b. Complete the second pair using the same relationship.

a. n/t is the formula for calculating the frequency

b. velocity

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Qn 3.

A tuning fork of 256 Hz excited and pressed against a table surface.

a) what is the frequency of vibration of the table?

b) what is this phenomenon called?

a) 256 Hz.

b) Induced

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Qn 4.

Which wave is propagated from the epicenter of an Earthquake ? Which instrument is used to measure the intensity of an Earthquake?

a) Seismic waves,

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Qn 5.

Sound travels 1020m through a medium in 3 seconds. Which could be the media among the following?Justify your answer.

(Aluminium, Steel, Air, Seawater)

Speed of sound v = 1020/30 = 340 m/s. So sound is travelled through air.

The speed of sound through all other mediums are very

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Qn 6.

The maximum displacement of a particle in a medium from its mean position is known as .............

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Qn 7.

The waves which needs a medium for propagation are .....................

(light waves, Electromagnetic waves, mechanical waves, Radio waves)

mechanical

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Qn 8.

Bhooming of sound is heard when the sound is produced in an empty hall. What is this phenomenon called?

Reverberation

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Qn 9.

The instruments shown below are working by making use of some sound phenomenon.

IMAGE

a) which sound phenomenon is made use of in this instrument?

b) The ceiling of certain halls are constructed with a curvature. What is it’s advantage?

a) Multiple reflection.

b) To avoid spreading sound all over the hall due to multiple

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Qn 10.

Tie one end of a rope to a window. Wind a ribbon on the rope. Hold the other end of the rope and move it up and down.The speed of the wave is constant.

Tie one end of a rope to a window. Wind a ribbon on the rope. Hold the other end of the rope and move it up and down.The speed of the wave is constant.

IMAGE

a) which wave is formed on the rope?

b) The ribbon completes 5 vibrations in a second. Then what is the velocity of the wave through the rope?

c) If the vibration of the rope is doubled what change will happen to the lenghth between A and B? Explain.

a) Transverse wave

b) V = fxƛ

v = 5 x 0.20

=1m/s

c) The distance will be

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Qn 11.

A particle ‘P’ in a medium is represented in the figure.

IMAGE

a) what is the direction of motion of the particle ‘P’ if the sound wave is travelling in the direction AB through the medium.

b) Increase of which characteristics of the travelling sound wave increases it’s frequency?

c) what is the frequency of the sound wave if the particle completes 6000 vibrations in a minute?

a. In the direction AB

b. Loudness.

c.

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Qn 12.

Graphic representation of a transverse wave is shown below.

IMAGE

Graph

a) Which particles are of same phase of vibration in the given graph?

( A-E , B-G , B-C , D-H, F-J) (1)

b) Find out the amplitude and wavelength from the graph.

Graphic representation of a transverse wave is shown below.

Graph

a) Which particles are of same phase of vibration in the given graph?

( A-E , B-G , B-C , D-H, F-J)

b) Find out the amplitude and wavelength from the graph.

a) A-E, D-H

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Qn 13.

Observe the representation of waves formed on the surface of water .(Speed of waves in the water is taken as 1500m/s)

IMAGE

a) Which wave is formed on the surface of water?

b) If the diameter of the container is 90cm, what is the frequency of the wave?

c) If the same sound passes with a speed of 2500m/s through water after adding some salt, what change will happen to its wavelength?

Observe the representation of waves formed on the surface of water .(Speed of waves in the water is taken as 1500m/s)

a) Which wave is formed on the surface of water?

b) If the diameter of the container is 90cm, what is the frequency of the wave?

c) If the same sound passes with a speed of 2500m/s through water after adding some salt, what change will happen to its wavelength?

Observe the representation of waves formed on the surface of water .(Speed of waves in the water is taken as 1500m/s)

a) Which wave is formed on the surface of water?

b) If the diameter of the container is 90cm, what is the frequency of the wave?

c) If the same sound passes with a speed of 2500m/s through water after adding some salt, what change will happen to its wavelength?

a) Transverse/ Mechanical

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Qn 14.

a) Write two problems raising by multiple reflection of sound in auditoriums (1)

b) Write two methods to solve this.

a) Echo, Reverberation

or any Equivalent idea

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Qn 15.

Fill up the blanks suitably

Sound waves in air       :    Longitudinal form

Waves on the surface of water: .................................

Transverse

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Qn 16.

Diagrams of some musical instruments are given

IMAGE

Diagrams

a) What is known as the vibration of sound board of Guitar and air inside a Chenda?

b) Explain this phenomenon.

a) Forced vibration

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Qn 17.

The waves which are responsible for the earthquake originate from the epic centre of the earthquake .

a. Write down the name of these waves.

b.  Name the instrument which is used to measure the intensity of the earthquake

a. Seismic waves

b.

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Qn 18.

Solve the problems given below.

a) Calculate the velocity of a wave with a frequency of 256Hz and wave length 1.5m .

b) What change will occur to the wavelength of the above wave ,if the frequency is increased to 512Hz without changing the medium ?

c) Where the wavelength will be more when a sound wave from a tuning fork of frequency 256Hz travels through air and steel? Explain

( speed of sound: In steel – 5941m/s, In Air – 343m/s)

a) V = fxƛ (1/2)

256x1.5 = 384m/s

b) ƛ = v/f (1/2)

= 384/512 = 0.75m

c) Wavelength is more when sound is

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Qn 19.

Graphic representation of a sound wave reaching the ears of a boy sitting at a distance buzzer source is given below.

IMAGE

a. What is the direction of propagation of particles in the medium when sound is travelling through air?

b. What is the frequency of the wave if it’s speed through air 350m/s?

c. Howlong it will take for the sound to reach the ears of the boy if he is sitting 100m away from the buzzer source?

d. What changes for the medium can be suggested to make the boy hear the same sound in less time from the same distance.

a. Particles are vibrating parallel to the propagation of sound.

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Qn 20.

Give scientific explanation for the life situations below by making use of the hints given.

a) Glass window panes will break at times when thunder strikes .why?

(Hints. Natural frequency,Amplitude of vibration, Resonance, Forced vibration)

b) Some special arrangements are made to hear the sound clearly inside large halls.

( Hints: Carpets, Acoustics of buildings, Reflection of sound, Reverberation)

a. Window panes are subjected to forced vibration during thunder. Some times the natural frequency of thunder will match the natural

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Qn 21.

The sound produced by a tuning fork of 480Hz travels with a speed of 360m/s through air. Then

a. What is the wavelength of the wave through air?

b. If the length of the air column through which the sound travelled is 3m, How many compressions will be there?

a. ƛ =v/f = 360/480 = 0.75m

b. ƛ = 0.75m. Therefore in 3m 3/0.75 =