MCQOPTIONS
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MCQOPTIONS
This section includes 114 Mcqs, each offering curated multiple-choice questions to sharpen your Physics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
A wave motion has the function \[y={{a}_{0}}\sin (\omega \,t-kx)\]. The graph in figure shows how the displacement y at a fixed point varies with time t. Which one of the labelled points shows a displacement equal to that at the position \[x=\frac{\pi }{2k}\] at time t = 0 |
| A. | P |
| B. | Q |
| C. | \[2000\,\,{AA}\] |
| D. | S |
| Answer» C. \[2000\,\,{AA}\] | |
| 2. |
The equation \[y=A{{\cos }^{2}}\left( 2\pi \ nt-2\pi \frac{x}{\lambda } \right)\] represents a wave with [KCET 2002] |
| A. | Amplitude A/2, frequency \[2n\] and wavelength \[\lambda /2\] |
| B. | Amplitude A/2, frequency \[2n\] and wavelength \[\lambda \] |
| C. | 6 |
| D. | Amplitude A, frequency \[n\] and wavelength \[\lambda \] |
| Answer» B. Amplitude A/2, frequency \[2n\] and wavelength \[\lambda \] | |
| 3. |
The equation of displacement of two waves are given as \[{{y}_{1}}=10\sin \left( 3\pi t+\frac{\pi }{3} \right)\]; \[{{y}_{2}}=5(\sin 3\pi t+\sqrt{3}\cos 3\pi t)\]. Then what is the ratio of their amplitudes [AIIMS 1997; Haryana PMT 2000] |
| A. | 1 : 2 |
| B. | 2 : 1 |
| C. | 550 Hz |
| D. | None of these |
| Answer» D. None of these | |
| 4. |
The correct graph between the frequency n and square root of density (r) of a wire, keeping its length, radius and tension constant, is |
| A. | |
| B. | |
| C. | 80o |
| D. | |
| Answer» D. | |
| 5. |
Which of the following curves represents correctly the oscillation given by \[y={{y}_{0}}\sin (\omega \,t-\varphi )\], where \[0<\varphi <90\] |
| A. | A |
| B. | B |
| C. | The amplitudes are not equal |
| D. | D |
| Answer» E. | |
| 6. |
The figure shows four progressive waves A, B, C, and D with their phases expressed with respect to the wave A. It can be concluded from the figure that [CPMT 1986, 88] |
| A. | The wave C is ahead by a phase angle of p/2 and the wave B lags behind by a phase angle of p /2 |
| B. | The wave C lags behind by a phase angle of p/2 and the wave B is ahead by a phase angle of p /2 |
| C. | \[1\,:\frac{4}{9\,{{\pi }^{2}}}:\frac{4}{25\,{{\pi }^{2}}}\] |
| D. | The wave C lags behind by a phase angle of pand the wave B ahead by a phase angle of p |
| Answer» C. \[1\,:\frac{4}{9\,{{\pi }^{2}}}:\frac{4}{25\,{{\pi }^{2}}}\] | |
| 7. |
The diagram below shows an instantaneous position of a string as a transverse progressive wave travels along it from left to right Which one of the following correctly shows the direction of the velocity of the points 1, 2 and 3 on the string |
| A. | \[1\text{ -}\,\to ~2\,\text{-}\,\to 3\,\text{-}\,\to \] |
| B. | \[1\text{ -}\,\to ~2\,\text{-}\leftarrow 3\,\text{-}\,\to \] |
| C. | \[3000\,\,{AA}\] |
| D. | \[1\text{ -}\downarrow ~2\,\text{-}\uparrow 3\,\text{-}\downarrow \] |
| Answer» E. | |
| 8. |
Two tuning forks P and Q are vibrated together. The number of beats produced are represented by the straight line OA in the following graph. After loading Q with wax again these are vibrated together and the beats produced are represented by the line OB. If the frequency of P is 341Hz, the frequency of Q will be |
| A. | 341 Hz |
| B. | 338 Hz |
| C. | 256 : 16 : 196 |
| D. | None of the above |
| Answer» D. None of the above | |
| 9. |
An observer is moving towards the stationary source of sound, then [MH CET 2001] |
| A. | Apparent frequency will be less than the real frequency |
| B. | Apparent frequency will be greater than the real frequency |
| C. | 8400 nm |
| D. | Only the quality of sound will change |
| Answer» C. 8400 nm | |
| 10. |
A whistle revolves in a circle with an angular speed of 20 rad/sec using a string of length 50 cm. If the frequency of sound from the whistle is 385 Hz, then what is the minimum frequency heard by an observer, which is far away from the centre in the same plane? (v = 340 m/s) [CBSE PMT 2002] |
| A. | 333 Hz |
| B. | 374 Hz |
| C. | 4.5 mm |
| D. | 394 Hz |
| Answer» C. 4.5 mm | |
| 11. |
A siren placed at a railway platform is emitting sound of frequency 5 kHz. A passenger sitting in a moving train A records a frequency of 5.5 kHz while the train approaches the siren. During his return journey in a different train B he records a frequency of 6.0 kHz while approaching the same siren. The ratio of the velocity of train B to that of train A is [IIT-JEE (Screening) 2002] |
| A. | 242/252 |
| B. | 2 |
| C. | 18 |
| D. | 11/6 |
| Answer» C. 18 | |
| 12. |
A source is moving towards an observer with a speed of 20 m/s and having frequency of 240 Hz. The observer is now moving towards the source with a speed of 20 m/s. Apparent frequency heard by observer, if velocity of sound is 340 m/s, is [CPMT 2000; KCET 2001; MH CET 2004] |
| A. | 240 Hz |
| B. | 270 Hz |
| C. | 2 cm, 4 cm |
| D. | 360 Hz |
| Answer» C. 2 cm, 4 cm | |
| 13. |
Two sirens situated one kilometer apart are producing sound of frequency 330 Hz. An observer starts moving from one siren to the other with a speed of 2 m/s. If the speed of sound be 330 m/s, what will be the beat frequency heard by the observer [RPMT 1996; CPMT 2002] |
| A. | 8 |
| B. | 4 |
| C. | 4 : 1 |
| D. | 1 |
| Answer» C. 4 : 1 | |
| 14. |
The driver of a car travelling with speed 30 metres per second towards a hill sounds a horn of frequency 600 Hz. If the velocity of sound in air is 330 metres per second, the frequency of the reflected sound as heard by the driver is [MP PMT 1996] |
| A. | 720 Hz |
| B. | 555.5 Hz |
| C. | (ii) and (iv) |
| D. | 500 Hz |
| Answer» B. 555.5 Hz | |
| 15. |
A boy is walking away from a wall towards an observer at a speed of 1 metre/sec and blows a whistle whose frequency is 680 Hz. The number of beats heard by the observer per second is (Velocity of sound in air = 340 metres/sec [MP PMT 1995] |
| A. | Zero |
| B. | 2 |
| C. | \[3.138\times {{10}^{-7}}m\] |
| D. | 4 |
| Answer» E. | |
| 16. |
A source of sound of frequency n is moving towards a stationary observer with a speed S. If the speed of sound in air is V and the frequency heard by the observer is \[{{n}_{1}}\], the value of \[{{n}_{1}}/n\] is [MP PMT 1997] |
| A. | \[(V+S)/V\] |
| B. | \[V/(V+S)\] |
| C. | \[3000\,\,{AA}\] |
| D. | \[V/(V-S)\] |
| Answer» E. | |
| 17. |
A motor car blowing a horn of frequency 124vib/sec moves with a velocity 72 km/hr towards a tall wall. The frequency of the reflected sound heard by the driver will be (velocity of sound in air is 330 m/s) [MP PET 1997] |
| A. | 109 vib/sec |
| B. | 132 vib/sec |
| C. | \[3.3\,\,{AA}\] |
| D. | 248 vib/sec |
| Answer» D. 248 vib/sec | |
| 18. |
A source of sound S of frequency 500 Hz situated between a stationary observer O and a wall W, moves towards the wall with a speed of 2 m/s. If the velocity of sound is 332 m/s, then the number of beats per second heard by the observer is (approximately) |
| A. | 8 |
| B. | 6 |
| C. | \[4.00\,\,{AA}\] |
| D. | 2 |
| Answer» C. \[4.00\,\,{AA}\] | |
| 19. |
A source of sound S is moving with a velocity 50m/s towards a stationary observer. The observer measures the frequency of the source as 1000 Hz. What will be the apparent frequency of the source when it is moving away from the observer after crossing him ? The velocity of sound in the medium is 350 m/s [MP PMT 1994] |
| A. | 750 Hz |
| B. | 857 Hz |
| C. | \[\frac{\lambda }{3}\] |
| D. | 1333 Hz |
| Answer» B. 857 Hz | |
| 20. |
A source of sound is moving with constant velocity of 20 m/s emitting a note of frequency 1000 Hz. The ratio of frequencies observed by a stationary observer while the source is approaching him and after it crosses him will be [MP PET 1994] |
| A. | 9 : 8 |
| B. | 8 : 9 |
| C. | 7.6 mm |
| D. | 9 : 10 (Speed of sound v = 340 m/s) |
| Answer» B. 8 : 9 | |
| 21. |
The Doppler's effect is applicable for [AFMC 1998] |
| A. | Light waves |
| B. | Sound waves |
| C. | If assertion is true but reason is false. |
| D. | Both (a) and (b) |
| Answer» E. | |
| 22. |
An observer while going on scooter hears sound of two sirens of same frequencies from two opposite directions. If he travels along the direction of one of the siren, then he |
| A. | Listens resonance |
| B. | Listens beats |
| C. | If assertion is true but reason is false. |
| D. | Will listen intensive sound due to constructive interference |
| Answer» C. If assertion is true but reason is false. | |
| 23. |
A source of frequency 150 Hz is moving in the direction of a person with a velocity of 110 m/s. The frequency heard by the person will be (speed of sound in medium = 330 m/s) [CPMT 1989; RPET 2001] |
| A. | 225 Hz |
| B. | 200 Hz |
| C. | If assertion is true but reason is false. |
| D. | 100 Hz |
| Answer» B. 200 Hz | |
| 24. |
A source of sound emitting a note of frequency 200 Hz moves towards an observer with a velocity v equal to the velocity of sound. If the observer also moves away from the source with the same velocity v, the apparent frequency heard by the observer is [MP PMT 1990] |
| A. | 50 Hz |
| B. | 100 Hz |
| C. | If assertion is true but reason is false. |
| D. | 200 Hz |
| Answer» E. | |
| 25. |
Suppose that the speed of sound in air at a given temperature is 400 m/sec. An engine blows a whistle at 1200 Hz frequency. It is approaching an observer at the speed of 100 m/sec. What is the apparent frequency as heard by the observer [CPMT 1983; DPMT 2001] |
| A. | 600 Hz |
| B. | 1200 Hz |
| C. | If assertion is true but reason is false. |
| D. | 1600 Hz |
| Answer» E. | |
| 26. |
The speed of sound in air at a given temperature is 350 m/s. An engine blows whistle at a frequency of 1200 cps. It is approaching the observer with velocity 50 m/s. The apparent frequency in cps heard by the observer will be [CPMT 1976; RPET 1999; BHU 1997, 2001] |
| A. | 600 |
| B. | 1050 |
| C. | If assertion is true but reason is false. |
| D. | 2400 |
| Answer» D. 2400 | |
| 27. |
Doppler's effect will not be applicable when the velocity of sound source is |
| A. | Equal to that of the sound velocity |
| B. | Less than the velocity of sound |
| C. | |
| D. | Zero |
| Answer» D. Zero | |
| 28. |
Two passenger trains moving with a speed of 108 km/hour cross each other. One of them blows a whistle whose frequency is 750 Hz. If sound speed is 330 m/s, then passengers sitting in the other train, after trains cross each other will hear sound whose frequency will be [MP PMT 1991] |
| A. | 900 Hz |
| B. | 625 Hz |
| C. | C |
| D. | 800 Hz |
| Answer» C. C | |
| 29. |
A person feels 2.5% difference of frequency of a motor-car horn. If the motor-car is moving to the person and the velocity of sound is 320 m/sec, then the velocity of car will be [CPMT 1981; MP PET 1989] |
| A. | 8 m/s (approx.) |
| B. | 800 m/s |
| C. | The wave C is ahead by a phase angle of pand the wave B lags behind by a phase angle of p |
| D. | 6 m/s (approx.) |
| Answer» B. 800 m/s | |
| 30. |
A whistle sends out 256 waves in a second. If the whistle approaches the observer with velocity 1/3 of the velocity of sound in air, the number of waves per second the observer will receive [MP PET 1990; DPMT 2002] |
| A. | 384 |
| B. | 192 |
| C. | R |
| D. | 200 |
| Answer» B. 192 | |
| 31. |
A wire of \[9.8\times {{10}^{-3}}kg{{m}^{-1}}\] passes over a frictionless light pulley fixed on the top of a frictionless inclined plane which makes an angle of 30° with the horizontal. Masses m and M are tied at the two ends of wire such that m rests on the plane and M hangs freely vertically downwards. The entire system is in equilibrium and a transverse wave propagates along the wire with a velocity of 100 ms?1. Chose the correct option |
| A. | \[m=20\,kg\] |
| B. | \[m=5\,kg\] |
| C. | \[1\text{ -}\downarrow ~2\,\text{-}\downarrow 3\,\text{-}\downarrow \] |
| D. | \[m=7\,kg\] |
| Answer» B. \[m=5\,kg\] | |
| 32. |
Two speakers connected to the same source of fixed frequency are placed 2.0 m apart in a box. A sensitive microphone placed at a distance of 4.0m from their midpoint along the perpendicular bisector shows maximum response. The box is slowly rotated until the speakers are in line with the microphone. The distance between the midpoint of the speakers and the microphone remains unchanged. Exactly five maximum responses are observed in the microphone in doing this. The wavelength of the sound wave is |
| A. | 0.2 m |
| B. | 0.4 m |
| C. | 344 Hz |
| D. | 0.8 m |
| Answer» C. 344 Hz | |
| 33. |
An open pipe is in resonance in its 2nd harmonic with tuning fork of frequency\[{{f}_{1}}\]. Now it is closed at one end. If the frequency of the tuning fork is increased slowly from \[{{f}_{1}}\] then again a resonance is obtained with a frequency\[{{f}_{2}}\]. If in this case the pipe vibrates \[{{n}^{th}}\] harmonics then [IIT-JEE (Screening) 2005] |
| A. | \[n=3,\] \[{{f}_{2}}=\frac{3}{4}{{f}_{1}}\] |
| B. | \[n=3,\] \[{{f}_{2}}=\frac{5}{4}{{f}_{1}}\] |
| C. | 7 m/s |
| D. | \[n=5,\] \[{{f}_{2}}=\frac{3}{4}{{f}_{1}}\] |
| Answer» D. \[n=5,\] \[{{f}_{2}}=\frac{3}{4}{{f}_{1}}\] | |
| 34. |
16 tunning forks are arranged in the order of increasing frequencies. Any two successive forks give 8 beats per sec when sounded together. If the frequency of the last fork is twice the first, then the frequency of the first fork is [CBSE PMT 2000; MP PET 2001] |
| A. | 120 |
| B. | 160 |
| C. | 300 |
| D. | 220 |
| Answer» B. 160 | |
| 35. |
25 tunning forks are arranged in series in the order of decreasing frequency. Any two successive forks produce 3 beats/sec. If the frequency of the first turning fork is the octave of the last fork, then the frequency of the 21st fork is [Kerala (Engg.) 2001] |
| A. | 72 Hz |
| B. | 288 Hz |
| C. | Apparent frequency will be equal to real frequency |
| D. | 87 Hz |
| Answer» D. 87 Hz | |
| 36. |
Two identical wires have the same fundamental frequency of 400 Hz. when kept under the same tension. If the tension in one wire is increased by 2% the number of beats produced will be [JIPMER 1999] |
| A. | 4 |
| B. | 2 |
| C. | 385 Hz |
| D. | 1 |
| Answer» B. 2 | |
| 37. |
Consider ten identical sources of sound all giving the same frequency but having phase angles which are random. If the average intensity of each source is \[{{I}_{0}}\], the average of resultant intensity I due to all these ten sources will be [MP PMT 1990] |
| A. | \[I=100\,{{I}_{0}}\] |
| B. | \[I=10\,{{I}_{0}}\] |
| C. | 5/6 |
| D. | \[I=\sqrt{10}\,{{I}_{0}}\] |
| Answer» C. 5/6 | |
| 38. |
In a wave motion \[y=a\sin (kx-\omega t)\], y can represent [IIT-JEE 1999] |
| A. | Electric field |
| B. | Magnetic field |
| C. | 280 Hz |
| D. | Pressure |
| Answer» D. Pressure | |
| 39. |
Oxygen is 16 times heavier than hydrogen. Equal volumes of hydrogen and oxygen are mixed. The ratio of speed of sound in the mixture to that in hydrogen is [KCET 2004] |
| A. | \[\sqrt{\frac{1}{8}}\] |
| B. | \[\sqrt{\frac{32}{17}}\] |
| C. | 8 |
| D. | \[\sqrt{\frac{2}{17}}\] |
| Answer» B. \[\sqrt{\frac{32}{17}}\] | |
| 40. |
A light pointer fixed to one prong of a tuning fork touches a vertical plate. The fork is set vibrating and the plate is allowed to fall freely. If eight oscillations are counted when the plate falls through 10 cm, the frequency of the tuning fork is [IIT 1977; KCET 2002] |
| A. | 360 Hz |
| B. | 280 Hz |
| C. | \[(V-S)/V\] |
| D. | 56 Hz |
| Answer» E. | |
| 41. |
A source producing sound of frequency 170 Hz is approaching a stationary observer with a velocity 17 ms?1. The apparent change in the wavelength of sound heard by the observer is (speed of sound in air = 340 ms?1) [EAMCET (Engg.) 2000] |
| A. | 0.1m |
| B. | 0.2m |
| C. | 140 vib/sec |
| D. | 0.5m |
| Answer» B. 0.2m | |
| 42. |
Two whistles A and B produces notes of frequencies 660 Hz and 596 Hz respectively. There is a listener at the mid-point of the line joining them. Now the whistle B and the listener start moving with speed 30 m/s away from the whistle A. If speed of sound be 330 m/s, how many beats will be heard by the listener [RPET 1996] |
| A. | 2 |
| B. | 4 |
| C. | 4 |
| D. | 8 |
| Answer» C. 4 | |
| 43. |
Two cars are moving on two perpendicular roads towards a crossing with uniform speeds of 72 km/hr and 36 km/hr. If first car blows horn of frequency 280 Hz, then the frequency of horn heard by the driver of second car when line joining the cars make 45° angle with the roads; will be [RPET 1997] |
| A. | 321 Hz |
| B. | 298 Hz |
| C. | 1143 Hz |
| D. | 280 Hz |
| Answer» C. 1143 Hz | |
| 44. |
Two tuning forks have frequencies 450 Hz and 454 Hz respectively. On sounding these forks together, the time interval between successive maximum intensities will be [MP PET 1989; MP PMT 2003] |
| A. | 1/4 sec |
| B. | 1/2 sec |
| C. | 1 : 1 |
| D. | 2 sec |
| Answer» B. 1/2 sec | |
| 45. |
When a tuning fork of frequency 341 is sounded with another tuning fork, six beats per second are heard. When the second tuning fork is loaded with wax and sounded with the first tuning fork, the number of beats is two per second. The natural frequency of the second tuning fork is [MP PET 1989] |
| A. | 334 |
| B. | 339 |
| C. | Space waves |
| D. | 347 |
| Answer» E. | |
| 46. |
The frequencies of two sound sources are 256 Hz and 260 Hz. At t = 0, the intensity of sound is maximum. Then the phase difference at the time t = 1/16 sec will be |
| A. | Zero |
| B. | p |
| C. | Will not listen sound due to destructive interference |
| D. | p/4 |
| Answer» D. p/4 | |
| 47. |
The disc of a siren containing 60 holes rotates at a constant speed of 360 rpm. The emitted sound is in unison with a tuning fork of frequency [KCET 2005] |
| A. | 10 Hz |
| B. | 360 Hz |
| C. | 150 Hz |
| D. | 6 Hz |
| Answer» C. 150 Hz | |
| 48. |
When a tuning fork produces sound waves in air, which one of the following is same in the material of tuning fork as well as in air [AFMC 2005] |
| A. | Wavelength |
| B. | Frequency |
| C. | 150 Hz |
| D. | Amplitude |
| Answer» C. 150 Hz | |
| 49. |
Two vibrating tuning forks produce progressive waves given by \[{{Y}_{1}}=4\sin 500\pi t\]and \[{{Y}_{2}}=2\sin 506\pi t.\] Number of beats produced per minute is [CBSE PMT 2005] |
| A. | 360 |
| B. | 180 |
| C. | 1500 Hz |
| D. | 60 |
| Answer» C. 1500 Hz | |
| 50. |
When temperature increases, the frequency of a tuning fork [AIEEE 2002] |
| A. | Increases |
| B. | Decreases |
| C. | 1400 |
| D. | Increases or decreases depending on the material |
| Answer» C. 1400 | |