Questions in Short/Long Answer Questions
Q1) How does sound travel in air?
Answer:-
sound travel in air in form of longitudinal wave.
Q2) What is longitudinal wave?
Answer:-
When in a wave, particles of a medium vibrate about their mean positions in the direction of travel of wave called longitudinal wave.
Q4) Define the following terms:
(a) Amplitude
(b) Frequency
(c) Time period
Answer:-
(a) Amplitude- the maximum displacement of A vibrating particle from its rest or mean position is called amplitude . It is expressed in metre
(b) Frequency the number of complete vibrations that the vibrating particle make in one second is called frequency and is expressed in the symbol Hz
(c) Time period the time taken by A vibrating particle to complete one vibration is called its time period it is expressed in second
Q5) Obtain relationship between the time period and frequency.
Answer-
Time period =1/ frequency
Q6) Name three characteristics of a musical sound.
Answer-
three characteristics of a musical sound.-
i) Loudness
ii) pitch
iii) Quality
Q7) Name the quantity from below which determines the loudness of a sound wave:
(a) Wavelength
(b) Frequency, and
(c) Amplitude
Answer-
(c) Amplitude
Q8) How is loudness related to the amplitude of wave?
Answer-
loudness is directly proportional to (amplitude)²
Q9)If the amplitude of a wave is doubled, what will be the effect on its loudness?
Answer-
If the amplitude of a wave is doubled, its loudness will be four times.
Q10) How does the wave pattern of a loud note differ from a soft note? Draw a diagram.
Answer
Q11) Name the unit in which the loudness of sound is expressed?
Answer-
Decbel is the unit in which the loudness of sound is expressed .
Q12) Why is the loudness of sound heard by a plucked wire increased when mounted on a soundboard?
Answer-:-.
When a wire mounted on a sound board is plucked, the surface area of vibrating air increases so the sound becomes more loud.
Q13) State three factors on which loudness of sound heard by a listener depends.
Answer
three factors
i) Amplitude of sound
ii) distance between source of sound and listen
ii) surface area of a body
Q14) What determines the pitch of a sound?
Answer-
Frequency determines the pitch of a sound.
Q15) Name the characteristics of sound related to its frequency.
Answer- Pitch is the characteristics of sound related to its frequency
Q16) Name and define the characteristic which enables one to distinguish two sounds of same loudness, but of different frequencies, given by the same instrument.
Amswer-
Quality is the characteristic which enables one to distinguish two sounds of same loudness, but of different frequencies, given by the same instrument.
Q17) Draw a diagram to show the wave pattern of high pitch note and a low pitch note, but of the same loudness.
Anxwet-
Q18) How is it possible to detect the filling of a bucket under a water tap by hearing the sound standing at a distance?
Answer-
The pitch of the sound of water filling in a bucket increases as the water in the bucket rises, and the length of the air column decreases.
Q19) The frequencies of notes given by flute, guitar and trumpet are respectively 400 Hz, 200 Hz and 500 Hz. Which one of these has the highest pitch?
Answer-
Trumpet among three has the highest pitch as more frequency.
Q20) Figure shows two jars A and B containing water up to different heights. Which will produce sound of higher pitch when air is blown on them?
Answer:-
Jar B will produce sound of high pitch
Q21) Two identical guitars are played by two persons to give notes of the same pitch. Will they differ in quality? Give reason for your answer.
Answer - No , Two identical guitars are played by two persons to give notes of the same pitch. they will not differ in quality as same wave form.
Q22) Two musical notes of the same pitch and same loudness are played on two different instruments. Their wave patterns are as shown in figure.
How do they differ in (a) loudness (b) pitch and (c) quality
Answer
(a) Loudness of each is the same as the amplitude is the same. (b) Pitch of each is the same. (c) Quality is different as the wave form is different.
They differ by rhe characteristic of sound called Quality
Q23) Which characteristics of sound makes it possible to recognize a person by his voice without seeing him?
Answer- Quality
Q24) State the factors that determine
(a) The pitch of a note
(b) The loudness of the sound heard
(c) the quality of the note.
Answer-
(a) The pitch of a note- frequency
(b) The loudness of the sound heard - Amplitude
(c) the quality of the note- waveform
Q25) Name the characteristics of the sound affected due to a change in its
(a) amplitude (b) waveform (c) frequency
Answer-
(a) amplitude -Loudness
(b) waveform - Quality
(c) frequency- Pitch
Q26) Figure shows four waves A, B, C, and D
Name the wave which shows (a) a note from a musical instrument (b) a soft note (c) a shrill note.
Answer-
(a) a note from a musical instrument - D
(b) a soft note- A
(c) a shrill note- C
27) How is the pitch of sound in a guitar changed if (a) thin wire is used, (b) wire under less tension is used?
Answer-
thin wire is used, - high pitch
(b) wire under less tension is used- low pitch
C. Numericals
1. Two waves of the same pitch have amplitudes in the ratio 1:3. What will be the ratio of their i) loudness ii) pitch?
Answer- i) loudness depends on square of amplitude
L1/L2 = 1²/ 3²= 1:9
ii) pitch does not depend on amplitude.
Ratio is 1:1
2. Two waves have frequencies 256 Hz and 512 Hz, but same amplitude.Conpare their i) loudness and ii) pitch
Answer-
i) Loudness does not depend upon pitch .
Ratio will be 1:1
ii) pitch directly depended upon frequency.
P1:P2 = 256 : 512 = 1:2
3. Two waves have the same pitch but their amplitudes are in the ratio 1:2 .Draw a figure to show the two waves.
Answer-
4. Two waves of same amplitude have frequencies 256 Hz and 512 Hz respectively. Represent the two waves in the graphical form
Answer-
Figure a) representing 256 Hz wave
Figure b) representing 512 Hz wave
----'--------------------------
