Waves Practice Questions

Two open organ pipes of length $60 {\text{cm}}$ and $90 {\text{cm}}$ resonate at $6^{\;\text{th }\;}$ and $5^{\;\text{th }\;}$ harmonics respectively. The difference of frequencies for the given modes is _______ ${\text{Hz}}$.(Velocity of sound in air $=333 {\text{m}} / {\ s}$ )

A tuning fork resonates with a sonometer wire of length $1 {\text{m}}$ stretched with a tension of $6 {\text{N}}$. When the tension in the wire is changed to $54 {\text{N}}$, the same tuning fork produces 12 beats per second with it. The frequency of the tuning fork is ______${\text{Hz}}$. [1-Feb-2024 Shift 1]

A closed and an open organ pipe have same lengths. If the ratio of frequencies of their seventh overtones is $(\;\frac{a-1}{a})$ then the value of $a$ is ______.

A point source is emitting sound waves of intensity $16 \times 10^{-8} {\text{Wm}}^{-2}$ at the origin. The difference in intensity (magnitude only) at two points located at a distances of $2 {\text{m}}$ and $4 {\text{m}}$ from the origin respectively will be______ $\times 10^{-8} {\text{Wm}}^{-2}$. [30-Jan-2024 Shift 2]

A plane progressive wave is given by $y=2 \cos 2 \pi (330 t-x) m$. The frequency of the wave is :

A person driving car at a constant speed of $15 {\text{m}} / {\ s}$ is approaching a vertical wall. The person notices a change of $40 {\text{Hz}}$ in the frequency of his car's horn upon reflection from the wall. The frequency of horn is ${\text{Hz}}$. [6-Apr-2023 shift 1]

In an experiment with sonometer when a mass of $180 {\text{g}}$ is attached to the string, it vibrates with fundamental frequency of $30 {\text{Hz}}$. When a mass ${\text{m}}$ is attached, the string vibrates with fundamental frequency of $50 {\text{Hz}}$. The value of ${\text{m}}$ is ________ g. [13-Apr-2023 shift 2]

A person observes two moving trains, 'A' reaching the station and ' ${\text{B}}$ ' leaving the station with equal speed of $30 {\text{m}} / {\ s}$. If both trains emit sounds with frequency $300 {\text{Hz}}$, (Speed of sound : $330 {\text{m}} / {\ s}$ ) approximate difference of frequencies heard by the person will be : [29-Jan-2023 Shift 1]

The fundamental frequency of vibration of a string stretched between two rigid support is $50 {\text{Hz}}$. The mass of the string is $18 {\text{g}}$ and its linear mass density is $20 {\text{g}} / {\text{m}}$. The speed of the transverse waves so produced in the string is _______ ${\text{ms}}^{-1}$ [15-Apr-2023 shift 1]

27. The distance between two consecutive points with phase difference of $60^{\circ}$ in a wave of frequency $500 {\text{Hz}}$ is $6.0 {\text{m}}$. The velocity with which wave is traveling is ________ ${\text{km}} / {\ s}$ [25-Jan-2023 Shift 1]

A train blowing a whistle of frequency $320 {\text{Hz}}$ approaches an observer standing on the platform at a speed of $66 {\text{m}} / {\ s}$. The frequency observed by the observer will be (given speed of sound $=330 {\text{ms}}^{-1}$ ) ________ ${\text{Hz}}$. [25-Jan-2023 Shift 2]

An organ pipe $40 {\text{cm}}$ long is open at both ends. The speed of sound in air is $360 {\text{ms}}^{-1}$. The frequency of the second harmonic is ________ ${\text{Hz}}$. [8-Apr-2023 shift 1]

A car P travelling at $20 {\text{ms}}^{-1}$ sounds its horn at a frequency of $400 {\text{Hz}}$. Another car ${\text{Q}}$ is travelling behind the first car in the same direction with a velocity $40 {\text{ms}}^{-1}$. The frequency heard by the passenger of the car ${\text{Q}}$ is approximately $[Take, velocity of sound $=360 {\text{ms}}^{-1}$ ]$ [11-Apr-2023 shift 2]

The equation of wave is given by $Y=10^{-2} sin \;2 \pi (160 t-0.5 x+\pi / 4)$ where ${\text{x}}$ and ${\text{Y}}$ are in ${\text{m}}$ and ${\text{t}}$ in ${\ s}$. The speed of the wave is ________ ${\text{km}} {\text{h}}^{-1}$. [11-Apr-2023 shift 1]

The engine of a train moving with speed $10 {\text{ms}}^{-1}$ towards a platform sounds a whistle at frequency $400 {\text{Hz}}$. The frequency heard by a passenger inside the train is : (neglect air speed. Speed of sound in air $=330 {\text{ms}}^{-1}$ ) [8-Apr-2023 shift 1]

For a certain organ pipe, the first three resonance frequencies are in the ratio of $1: 3: 5$ respectively. If the frequency of fifth harmonic is $405 {\text{Hz}}$ and the speed of sound in air is $324 {\text{ms}}^{-1}$ the length of the organ pipe is ________ ${\text{m}}$ [12-Apr-2023 shift 1]

A transverse harmonic wave on a string is given by $y(x, t)=5 sin \;(6 {\text{t}}+0.003 {\text{x}})$where ${\text{x}}$ and ${\text{y}}$ are in ${\text{cm}}$ and ${\text{t}}$ in sec. The wave velocity is _______ ${\text{ms}}^{-1}$. [10-Apr-2023 shift 1]

A travelling wave is described by the equation ${\text{y}}( {\text{x}}, {\text{t}})=[0.05 sin \;(8 {\text{x}}-4 {\text{t}}] {\text{m}}$The velocity of the wave is : [all the quantities are in SI unit] [24-Jan-2023 Shift 1]