A cylindrical tube $(L = 120\,cm.)$ is resonant with a tuning fork of frequency $330\,Hz$. If it is filling by water then to get resonance minimum length of water column is ..... $cm$ $(V_{air} = 330\,m/s)$
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The frequency of transverse vibrations in a stretched string is $200 Hz$. If the tension is increased four times and the length is reduced to one-fourth the original value, the frequency of vibration will be .... $Hz$
A wave equation is $y = 10^{-4}\, sin\, (60 t + 2x)$ Where $x$ and $y$ are in $metres$ and $t$ is in $sec$ . Which of the following statements is correct ?
A locomotive approaching a crossing at a speed of $20 \,ms ^{-1}$ sounds a whistle of frequency $640 \,Hz$ when $1 \,km$ from the crossing. There is no wind and the speed of sound in air is $330 \,ms ^{-1}$. What frequency is heard by an observer $\sqrt{3} \,km$ on the straight road from the crossing at right angle ......... $Hz$
$Assertion :$ Sound waves cannot travel in vacuum but light can travel in vacuum.
$Reason :$ Sound waves are longitudinal waves and they cannot be polarised but electromagentic waves are transverse and they can be polarised.
A policemen buzz a whistle of frequency $400\ Hz$. A car driver is approaching the policemen. The speed of car is $54\ kmh^{-1}$. The change in frequency experienced by the driver, when driver approaches the policemen and after he crosses the policemen, is ... $Hz$ [Velocity of sound is $350\ ms^{-1}$]
Statement$-1:$ Two longitudinal waves given by equations $y _{1}( x , t )=2 a \sin (\omega t - kx )$ and $y _{2}( x , t )= a \sin (2 \omega t -2 kx )$ will have equal intensity.
Statement$-2:$ Intensity of waves of given frequency in same medium is proportional to square of amplitude only.