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Sound — Science STD 9 — Question

Gujarat BoardEnglish MediumSTD 9ScienceSound4 Marks
Question
  • The distance between two consecutivecompressions $(C)$ or two consecutiverarefactions $(R)$ is called the wavelength.The wavelength is usually represented by λ (Greek letter lambda). Its $SI$ unit is meter $(m)$.
    •If we can count the number of the compressions or rarefactions that cross us per unit time, we will get the frequency of the sound wave. It is usually represented by υ (Greek letter, nu). $SI$ unit is hertz (symbol, Hz).
    •The time taken for one complete oscillation is called the time period of the sound wave. It is represented by the symbol T. Its $SI$ unit is second $(s)$.Frequency and time period are related asfollows: $υ=1/\lambda $
    •The speed of sound is defined as the distance which a point on a wave, such as a compression or a rarefaction, travels per unit time.
speed, $v$ = distance / time
$v= \lambda /T = υ\lambda $​​​​​​​
(i) SI unit of wavelength
$(a)$ m
$(b)$ Hertz
$(c)$ m/s
$(d)$ None of these
(ii)SI unit of Frequency
$(a)$ m
$(b)$ Hertz
$(c)$ m/s
$(d)$ None of these
(iii) Relation between frequency and time is given by
$(a)$ frequency and time are directly proportional
$(b)$ frequency and time are inversely proportional
$(c)$ There is no relation between them
$(d)$ None of these
$(iv)$ Define speed of sound. Give its formula in terms of wavelength and frequency
$(v)$ Define wavelength frequency and time period of longitudinal wave
 
✓

Answer

  • $(i) a$
    $(ii) b$
    $(iii) b$
    $(iv)$ The speed of sound is defined as the distance which a point on a wave, such as a compression or a rarefaction, travels per unit time.
    speed, $v$ = distance / time
    $v= \lambda /T = υ\lambda .$
    $(v)$ The distance between two consecutive compressions $(C)$ or two consecutive rarefactions $(R)$ is called the wavelength.The wavelength is usually represented by $\lambda $ (Greek letter lambda). Its $SI$ unit is meter $(m)$.
    If we can count the number of the compressions or rarefactions that cross us per unit time, we will get the frequency of the sound wave. It is usually represented by $υ$ (Greek letter, nu). $SI$ unit is hertz (symbol, $Hz$).
    The time taken for one complete oscillation is called the time period of the sound wave. It is represented by the symbol $T$. Its $SI$ unit is second $(s)$.Frequency and time period are related as follows: $υ= 1/\lambda $.

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