All STD 11 - Waves and sound questions
Newest firstShowing 101–139 of 139 questions
- 101. A small speaker delivers \(2\, W\) of audio output. At what distance from the speaker will one detect \(120\, dB\) intensity sound ... \(cm\) ? [Given reference intensity of sound as \(10^{-12}\,W/m^2\)] 2019 Easy
- 102. A source of sound \(S\) is moving with the velocity of \(50\,m/s\) towards a stationary observer. The observer measures the frequency of the sound as \(1000\,Hz.\) What will be the apparent frequency of the source when it is moving away from the observer after crossing him ... \(Hz\) ? (Take velocity of sound in air is \(350\,m/s\) ) 2019 Easy
- 103. A stationary source emits sound waves of frequency \(500\, Hz\). Two observers moving along a line passing through the source detect sound to be of frequencies \(480\, Hz\) and \(530\, Hz\). Their respective speeds are, in \(m\,s^{-1}\) (Given speed of sound \(= 300\, m/s\)) 2019 Medium
- 104. A string \(2.0\, m\) long and fixed at its end is driven by a \(240\, Hz\) vibrator. The string vibrates in its third harmonic mode. The speed of the wave and its fundamental frequency is 2019 Easy
- 105. A string is clamed at both the ends and it is vibrating in its \(4^{th}\) harmonic. The equation of the stationary wave is \(Y =0.3\,sin\,(0.157\,x) \,cos\,(200\pi t)\). The length of the string is ..... \(m\) (all quantities are in \(SI\) units) 2019 Easy
- 106. A string of length \(1\, m\) and mass \(5\, g\) is fixed at both ends. The tension in the string is \(8.0\, N\). The string is set into vibration using an external vibrator of frequency \(100\, Hz\). The separation between successive nodes on the string is close to .... \(cm\) 2019 Medium
- 107. A submarine \((A)\) travelling at \(18\, km/hr\) is being chased along the line of its velocity by another submarine \((B)\) travelling at \(27\, km/hr\). \(B\) sends a sonar signal of \(500\, Hz\) to detect \(A\) and receives a reflected sound of frequency \(v\). The value of \(v\) is close to ... \(Hz\) (Speed of sound in water \(= 1500\, ms^{-1}\)) 2019 Hard
- 108. A train moves towards a stationary observer with speed \(34\, m/s\). The train sounds a whistle and its frequency registered by the observer is \(f_1\). If the speed of the train is reduced to \(17\, m/s\), the frequency registered is \(f_2\). If speed of sound is \(340\, m/s\), then the ratio \(f_1/f_2\) is 2019 Hard
- 109. A travelling harmonic wave is represented by the equation \(y(x, t) = 10^{-3}\,sin\,(50t + 2x)\), where \(x\) and \(y\) are in meter and \(t\) is in seconds. Which of the following is a correct statement about the wave? 2019 Hard
- 110. A tuning fork of frequency \(480\, Hz\) is used in an experiment for measuring speed of sound \((\nu )\) in air by resonance tube method. Resonance is observed to occur at two successive lengths of the air column, \({\ell _1} = 30\,cm\) and \({\ell _2} = 70\,cm\). Then \(\nu\) is equal to ..... \(ms^{-1}\) 2019 Hard
- 111. A wire of length \(2\,L\) is made by joining two wires \(A\) and \(B\) of same lengths but different radii \(r\) and \(2r\) and made of the same material. It is vibrating at a frequency such that the joint of the two wires forms a node. If the number of antinodes in wire \(A\) is \(p\) and that in \(B\) is \(q\) then the ratio \(p : q\) is
2019 Hard - 112. Equation of travelling wave on a stretched string of linear density \(5\,g/m\) is \(y = 0.03\,sin\,(450\,t -9x)\) where distance and time are measured in \(SI\) united. The tension in the string is ... \(N\) 2019 Medium
- 113. The pressure wave, \(P = 0.01\,sin\,[1000t -3x]\,Nm^{-2},\) corresponds to the sound produced by a vibrating blade on a day when atmospheric temperature is \(0\,^oC.\) On some other day when temperature is \(T,\) the speed of sound produced by the same blade and at the same frequency is found to be \(336 \,ms^{-1}\). Approximate value of \(T\) is .... \(^oC\) 2019 Medium
- 114. Two cars \(A\) and \(B\) are moving away from each other in opposite directions. Both the cars are moving with a speed of \(20\, ms^{-1}\) with respect to the ground. If an observer in car \(A\) detects a frequency \(2000\, Hz\) of the sound coming from car \(B\), what is the natural frequency of the sound source of car \(B\) .... \(Hz\) ? (speed of sound in air \(= 340\, ms^{-1}\)) 2019 Hard
- 115. Two sources of sound \(S_1\) and \(S_2\) produce sound waves of same frequency \(660\, Hz\). A listener is moving from source \(S_1\) towards \(S_2\) with a constant speed \(u\, m/s\) and he hears \(10\, beats/s\). The velocity of sound is \(330\, m/s\). Then, \(u\) equals ... \(m/s\) 2019 Medium
- 116. \(5\, beats/ second\) are heard when a turning fork is sounded with a sonometer wire under tension, when the length of the sonometer wire is either \(0.95\,m\) or \(1\,m\) . The frequency of the fork will be ... \(Hz\) 2018 Medium
- 117. A granite rod of \(60\ cm\) length is clamped at its middle point and is set into longitudinal vibrations. The density of granite is \(2.7 \times 10^3 \) \(kg/m^3\) and its Young's modulus is \(9.27 \times 10^{10}\) \(Pa\) What will be the fundamental frequency of the longitudinal vibrations .... \(kHz\) ? 2018 Hard
- 118. A tuning fork vibrates with frequency \(256\, Hz\) and gives one beat per second with the third normal mode of vibration of an open pipe . What is the length of the pipe? ... \(cm\) (Speed of sound of air is \(340\, ms^{-1}\)) 2018 Easy
- 119. The end correction of a resonance column is \(1\,cm.\) If the shortest length resonating with the tuning fork is \(10\,cm,\) the next resonating length should be ..... \(cm\) 2018 Hard
- 120. Two sitar strings, \(A\) and \(B,\) playing the note \('Dha'\) are slightly out of tune and produce beats and frequency \(5\,Hz.\) The tension of the string \(B\) is slightly increased and the beat frequency is found to decrease by \(3\,Hz\) . If the frequency of \(A\) is \(425\,Hz,\) the original frequency of \(B\) is ... \(Hz\) 2018 Easy
- 121. A standing wave is formed by the superposition of two waves travelling in opposite directions. The transverse displacement is given by \(y\left( {x,t} \right) = 0.5\sin\, \left( {\frac{{5\pi }}{4}x} \right)\,\cos\, \left( {200\,\pi t} \right)\). What is the speed of the travelling wave moving in the positive \(x\) direction .... \(m/s\) ? (\(x\) and \(t\) are in meter and second, respectively.) 2017 Hard
- 122. Two wires \(W_1\) and \(W_2\) have the same radius \(r\) and respective densities \({\rho _1}\) and \({\rho _2}\) such that \({\rho _2} = 4{\rho _1}\). They are joined together at the point \(O\), as shown in the figure. The combination is used as a sonometer wire and kept under tension \(T\). The point \(O\) is midway between the two bridges. When a stationary waves is set up in the composite wire, the joint is found to be a node. The ratio of the number of an tin odes formed in \(W_1\) to \(W_2\) is
2017 Medium - 123. A pipe open at both ends has a fundamental frequency \(f\) in air. The pipe is dipped vertically in water so that half of it is in water. The fundamental frequency of the air column is now ..... \(f\) 2016 Medium
- 124. A toy-car, blowing its horn, is moving with a steady speed of \(5\, m/s\) , away from a wall. An observer, towards whom the toy car is moving, is able to hear \(5\, beats\) per second. If the velocity of sound in air is \(340\, m/s\), the frequency of the horn of the toy car is close to ... \(Hz\) 2016 Medium
- 125. A uniform string oflength \(20\ m\) is suspended from a rigid support. A short wave pulse is introduced at its lowest end. It starts moving up the string. The time taken to reach the supports is (take \(g= 10 \) \(ms^{-2}\) ) 2016 Easy
- 126. Two engines pass each other moving in opposite directions with uniform speed of \(30\,m/s\) . One of them is blowing a whistle of frequency \(540\,Hz.\) Calculate the frequency heard by driver of second engine before they pass each other ... \(Hz\). Speed of sound is \(330\,m/sec\) 2016 Easy
- 127. A bat moving at \(10\,ms^{-1}\) towards a wall sends a sound signal of \(8000\,Hz\) towards it. On reflection it hears a sound of frequency \(f\). The value of \(f\) in \(Hz\) is close to (speed of sound \(= 320\,ms^{-1}\) ) 2015 Hard
- 128. A source of sound emits sound waves at frequency \(f_0\). It is moving towards an observer with fixed speed \(v_s\) (\(v_s < v\), where \(v\) is the speed of sound in air). If the observer were to move towards the source with speed \(v_0\), one of the following two graphs (\(A\) and \(B\)) will given the correct variation of the frequency \(f\) heard by the observer as \(v_0\) is changed The variation of \(f\) with \(v_0\) is given correctly by
2015 Easy - 129. A train is moving on a straight track with speed \(20\ ms^{-1}\). It is blowing its whistle at the frequency of \(1000\ Hz\). The percentage change in the frequency heard by a person standing near the track as the train passes him is ( speed of sound \(=320\) \(ms^{-1}\) ) close to .... \(\%\) 2015 Hard
- 130. A source of sound \(A\) emitting waves of frequency \(1800\,Hz\) is falling towards ground with a terminal speed \(v.\) The observer \(B\) on the ground directly beneath the source receives waves of frequency \(2150\,Hz.\) The source \(A\) receives waves, reflected from ground of frequency nearly ..... \(Hz\) (Speed of sound \(= 343\,m/s\) ) 2014 Easy
- 131. A transverse wave is represented by \(y = \frac{{10}}{\pi }\,\sin \,\left( {\frac{{2\pi }}{T}t - \frac{{2\pi }}{\lambda }x} \right)\) For what value of the wavelength the wave velocity is twice the maximum particle velocity ..... \(cm\) ? 2014 Medium
- 132. The total length of a sonometer wire between fixed ends is \(110\, cm\). Two bridges are placed to divide the length of wire in ratio \(6 : 3 : 2\). The tension in the wire is \(400\, N\) and the mass per unit length is \(0.01\, kg/m\) . What is the minimum common frequency with Which three parts can vibrate ........... \(Hz\) ? 2014 Medium
- 133. Two factories are sounding their sirens at \(800\, Hz\) . A man goes from one factory to other at a speed of \(2\,m/s\). The velocity of sound is \(320\, m/s\). The number of beats heard by the person in one second will be 2014 Hard
- 134. \(A\) and \(B\) are two sources generating sound waves. A listener is situated at \(C\) . The frequency of the source at \(A\) is \(500\,Hz\) . \(A,\) now, moves towards \(C\) with a speed \(4\,m/s.\) The number of beats heard at \(C\) is \(6.\) When \(A\) moves away from \(C\) with speed \(4\,m/s,\) the number of beats heard at \(C\) is \(18.\) The speed of sound is \(340\,m/s.\) The frequency of the source at \(B\) is ..... \(Hz\)
2013 Medium - 135. A sonometer wire of length \(114\, cm\) is fixed at both the ends. Where should the two bridges be placed so as to divide the wire into three segments whose fundamental frequencies are in the ratio \(1 : 3 : 4\) ? 2013 Hard
- 136. A sonometer wire oflength \(1.5\ m\) is made of steel. The tension in it produces an elastic strain of \(1 \%\). What is the fundamental frequency of steel if density and elasticity of steel are \(7.7 \times 10^3 \) \(kg/m^3\) and \(2.2 \times 10^{11}\) \(N/m^2\) respectively? 2013 Easy
- 137. An engine approaches a hill with a constant speed. When it is at a distance of \(0.9\, km\), it blows a whistle whose echo is heard by the driver after \(5\, seconds\). If the speed of sound in air is \(330\, m/s\), then the speed of the engine is .... \(m/s\) 2013 Easy
- 138. In a transverse wave the distance between a crest and neighbouring trough at the same instant is \(4.0\, cm\) and the distance between a crest and trough at the same place is \(1 .0\, cm\) . The next crest appears at the same place after a time interval of \(0.4\,s\). The maximum speed of the vibrating particles in the medium is 2013 Easy
- 139. When two sound waves travel in the same direction in a medium, the displacements of a particle located at \('x'\) at time \('t'\) is given by \({y_1} = 0.05\,\cos \,\left( {0.50\,\pi x - 100\,\pi t} \right)\) \({y_2} = 0.05\,\cos \,\left( {0.46\,\pi x - 92\,\pi t} \right)\) then velocity is..... \(m/s\) 2013 Hard
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