Waves practice · Medium

Assertion: Longitudinal waves are called pressure waves.
Reason: Propagation of longitudinal waves through a medium involves changes in pressure (density of medium particles), when compressions and rarefactions are formed.

Three resonant frequencies of string with both rigid ends are 90,150 and $210 \mathrm{~Hz}$. If the length of the string is $80 \mathrm{~cm}$, what is the speed of the transverse wave in the string?

When a sound wave goes from one medium to another, the quantity that remains unchanged is

A pulse of a wave train travels along a stretched string and reaches the fixed end of the string. It will be reflected with

Assertion: Explosions on other planets are not heard on earth.
Reason: To hear distinct beats difference infrequencies of two sources should be less than 10.

The source producing sound and an observer both are moving along the direction of propagation of sound waves. If the respective velocities of sound, source and an observer are $v, v_s$ and $v_o$, then the apparent frequency heard by the observer will be: ($n=$ frequency of sound)

Statement-I: In propagation of sound waves, pressure amplitude is proportional to the displacement amplitude.
Statement-II: Suppose the source and observer both are stationary and wind is blowing in a direction from source to observer, then the observer detects an apparent increase in frequency.

The equation of a wave on a string of linear mass density $0.04\,\,kg{m^{ - 1}}$ is given by $y = 0.02\left( m \right)\,\,\sin \left[ {2\pi \left( {\frac{t}{{0.04\left( s \right)}} - \frac{x}{{0.50\left( m \right)}}} \right)} \right]$. The tension in the string is

If the speed of a wave doubles as it passes from shallow water deeper water, its wavelength will be

In a stationary wave

Assertion: The change in air pressure affects the speed of sound.
Reason: The speed of sound in a gas is proportional to square root of pressure.

A motorcyclist going around a circular track of radius $50 \mathrm{~m}$ with a speed of $25 \mathrm{~m} / \mathrm{s}$, is at a point ${X}$. A static siren at ${Y}$ is emitting sound of frequency ${n}$. How many times (approximately) in an hour will the motor cyclist hear the sound of actual frequency ${Y}?$

Two aeroplanes $A$ and $B$ are approaching cach other and their velocities are $108 \mathrm{~km} \mathrm{~h}^{-1}$ and $144 \mathrm{~km} \mathrm{~h}^{-1}$ respectively. The frequency of a note emitted by $A$ as heard by the passengers in $B$ is $1170 \mathrm{~Hz}$. Calculate the frequency of the note heard by the passenger in A. Velocity of sound $=350 \mathrm{~ms}^{-1}$.

The beats are the examples of

The amplitude of a wave is given by $A$ $= \frac{c}{{a + b + c}}$ . Resonance will occur when

Two organ (open) pipes of length 50 cm and 51 cm produce ‘6’ beats/s. Then the speed of sound is nearly

Two sound sources emit the sounds of same frequency $f$. An observer is at the mid-way between the sources on the line joining them. When he starts moving towards one source with speed ${v} / 20$, where ' $v$ ' is speed of sound, he hears 10 beats per second. The value of ' ${f}$ ' is

Assertion (A) : When a wave travels from a denser medium to rarer medium, then amplitude of oscillation increases.

Reason (R) : In denser medium, speed of wave is less compared to a rarer medium.

Two waves of same frequency and intensity superimpose with each other in opposite phases, then after superposition the

Velocity of sound is maximum in

The equation of a plane progressive waves is given by $y = 0.025\,\,\sin \left( {100\,t + 0.25x} \right)$. The frequency of this wave would be

Assertion: When a beetle moves along the sand within a few tens of centimeters of a sand scorpion, the scorpion immediately turns towards the beetle and dashes towards it.
Reason: When a beetle disturbs the sand, it sends pulses along the sand's surface. One set of pulses is longitudinal while the other set is transverse.

The pitch of a sound wave is related to its

Statement-I: When a sound wave is propagating through the medium, the pressure fluctuations are $/ 2$ out of phase with the displacements.
Statement-II: When a sound wave is propagating through the medium maximum pressure deviation occurs at the positions of zero displacement and no pressure change occur at the positions of maximum displacements.

What is the effect of humidity on sound waves when humidity increases?

A transverse wave of amplitude $0.50 \mathrm{~mm}$ and frequency $100 \mathrm{~Hz}$ is produced on a wire stretched to a tension of $100 \mathrm{~N}$. If the wave speed is $100 \mathrm{~ms}^{-1}$, what average power is the source transmitting to the wire?

Under identical conditions of pressure and density, the speed of sound is highest in a

Apparatus used to find out velocity of sound in gas is

Stationary waves' are so called because in them

The tones that are separated by three octaves have a frequency ratio of