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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 7651. |
A source and an observer move away from each other with a velocity of 10 m/s with respect to ground. If the observer finds the frequency of sound coming from the source as 1950 Hz, then actual frequency of the source is (velocity of sound in air = 340 m/s) [EAMCET 1997; MH CET 2000; AFMC 2000; CBSE PMT 2001] |
| A. | 1950 Hz |
| B. | 2068 Hz |
| C. | 2132 Hz |
| D. | 2486 Hz |
| Answer» C. 2132 Hz | |
| 7652. |
If source and observer both are relatively at rest and if speed of sound is increased then frequency heard by observer will [RPET 2000; J & K CET 2004] |
| A. | Increases |
| B. | Decreases |
| C. | Cannot be predicted |
| D. | Will not change |
| Answer» E. | |
| 7653. |
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 train?s speed is reduced to 17 m/s, the frequency registered is \[{{f}_{2}}\]. If the speed of sound is 340 m/s then the ratio \[{{f}_{1}}/{{f}_{2}}\] is [IIT-JEE (Screening) 2000] |
| A. | 18/19 |
| B. | 1/2 |
| C. | 2 |
| D. | 19/18 |
| Answer» E. | |
| 7654. |
A whistle of frequency 500 Hz tied to the end of a string of length 1.2 m revolves at 400 rev/min. A listener standing some distance away in the plane of rotation of whistle hears frequencies in the range (speed of sound = 340 m/s) [KCET 2000; AMU 1999; Pb. PET 2003] |
| A. | 436 to 586 |
| B. | 426 to 574 |
| C. | 426 to 584 |
| D. | 436 to 674 |
| Answer» B. 426 to 574 | |
| 7655. |
A source of sound of frequency 90 vibrations/ sec is approaching a stationary observer with a speed equal to 1/10 the speed of sound. What will be the frequency heard by the observer [MP PMT 2000] |
| A. | 80 vibrations/sec |
| B. | 90 vibrations/sec |
| C. | 100 vibrations/sec |
| D. | 120 vibrations/sec |
| Answer» D. 120 vibrations/sec | |
| 7656. |
A source of sound of frequency 500 Hz is moving towards an observer with velocity 30 m/s. The speed of sound is 330 m/s. the frequency heard by the observer will be [MP PET 2000; Kerala PMT 2005; UPSEAT 2005] |
| A. | 550 Hz |
| B. | 458.3 Hz |
| C. | 530 Hz |
| D. | 545.5 Hz |
| Answer» B. 458.3 Hz | |
| 7657. |
A source of sound emits waves with frequency f Hz and speed V m/sec. Two observers move away from this source in opposite directions each with a speed 0.2 V relative to the source. The ratio of frequencies heard by the two observers will be [MP PET 1990] |
| A. | 3 : 2 |
| B. | 2 : 3 |
| C. | 1 : 1 |
| D. | 4 : 10 |
| Answer» D. 4 : 10 | |
| 7658. |
A man sitting in a moving train hears the whistle of the engine. The frequency of the whistle is 600 Hz [JIPMER 1999] |
| A. | The apparent frequency as heard by him is smaller than 600 Hz |
| B. | The apparent frequency is larger than 600 Hz |
| C. | The frequency as heard by him is 600 Hz |
| D. | None of the above |
| Answer» D. None of the above | |
| 7659. |
A siren emitting sound of frequency 500 Hz is going away from a static listener with a speed of 50 m/sec. The frequency of sound to be heard, directly from the siren, is [AIIMS 1999; Pb. PMT 2003] |
| A. | 434.2 Hz |
| B. | 589.3 Hz |
| C. | 481.2 Hz |
| D. | 286.5 Hz |
| Answer» B. 589.3 Hz | |
| 7660. |
A source of sound and listener are approaching each other with a speed of 40 m/s. The apparent frequency of note produced by the source is 400 cps. Then, its true frequency (in cps) is (velocity of sound in air = 360 m/s) [KCET 1999] |
| A. | 420 |
| B. | 360 |
| C. | 400 |
| D. | 320 |
| Answer» E. | |
| 7661. |
A source of sound is travelling with a velocity 40 km/hour towards observer and emits sound of frequency 2000 Hz. If velocity of sound is 1220 km/hour, then what is the apparent frequency heard by an observer [AFMC 1997] |
| A. | 2210 Hz |
| B. | 1920 Hz |
| C. | 2068 Hz |
| D. | 2086 Hz |
| Answer» D. 2086 Hz | |
| 7662. |
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. | 6 |
| D. | 1 |
| Answer» C. 6 | |
| 7663. |
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. | 550 Hz |
| D. | 500 Hz |
| Answer» B. 555.5 Hz | |
| 7664. |
At what speed should a source of sound move so that stationary observer finds the apparent frequency equal to half of the original frequency [RPMT 1996] |
| A. | \[\frac{v}{2}\] |
| B. | 2v |
| C. | \[\frac{v}{4}\] |
| D. | v |
| Answer» E. | |
| 7665. |
An observer standing at station observes frequency 219 Hz when a train approaches and 184 Hz when train goes away from him. If velocity of sound in air is 340 m/s, then velocity of train and actual frequency of whistle will be [RPET 1997] |
| A. | \[15.5\,m{{s}^{-1}},\ 200\,Hz\] |
| B. | \[19.5\,m{{s}^{-1}},\ 205\,Hz\] |
| C. | \[29.5\,m{{s}^{-1}},\ 200\,Hz\] |
| D. | \[32.5\,m{{s}^{-1}},\ 205\,Hz\] |
| Answer» D. \[32.5\,m{{s}^{-1}},\ 205\,Hz\] | |
| 7666. |
An observer is moving away from source of sound of frequency 100 Hz. His speed is 33 m/s. If speed of sound is 330 m/s, then the observed frequency is [EAMCET (Engg.) 1995; CPMT 1999] |
| A. | 90 Hz |
| B. | 100 Hz |
| C. | 91 Hz |
| D. | 110 Hz |
| Answer» B. 100 Hz | |
| 7667. |
The frequency of a whistle of an engine is 600 cycles/sec is moving with the speed of 30 m/sec towards an observer. The apparent frequency will be (velocity of sound = 330 m/s) [MP PMT 1989] |
| A. | 600 cps |
| B. | 660 cps |
| C. | 990 cps |
| D. | 330 cps |
| Answer» C. 990 cps | |
| 7668. |
A whistle giving out 450 Hz approaches a stationary observer at a speed of 33 m/s. The frequency heard by the observer in Hz is [IIT 1997 Cancelled] |
| A. | 409 |
| B. | 429 |
| C. | 517 |
| D. | 500 |
| Answer» E. | |
| 7669. |
A vehicle with a horn of frequency n is moving with a velocity of 30 m/s in a direction perpendicular to the straight line joining the observer and the vehicle. The observer perceives the sound to have a frequency\[n+{{n}_{1}}\]. Then (if the sound velocity in air is 300 m/s) [CBSE PMT 1998; AIIMS 2000] |
| A. | \[{{n}_{1}}=10\,n\] |
| B. | \[{{n}_{1}}=0\] |
| C. | \[{{n}_{1}}=0.1\,n\] |
| D. | \[{{n}_{1}}=-0.1\,n\] |
| Answer» C. \[{{n}_{1}}=0.1\,n\] | |
| 7670. |
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. | \[(V-S)/V\] |
| D. | \[V/(V-S)\] |
| Answer» E. | |
| 7671. |
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. | 140 vib/sec |
| D. | 248 vib/sec |
| Answer» D. 248 vib/sec | |
| 7672. |
A table is revolving on its axis at 5 revolutions per second. A sound source of frequency 1000 Hz is fixed on the table at 70 cm from the axis. The minimum frequency heard by a listener standing at a distance from the table will be (speed of sound = 352 m/s) [MP PET 1996] |
| A. | 1000 Hz |
| B. | 1066 Hz |
| C. | 941 Hz |
| D. | 352 Hz |
| Answer» D. 352 Hz | |
| 7673. |
A source and listener are both moving towards each other with speed v/10, where v is the speed of sound. If the frequency of the note emitted by the source is f, the frequency heard by the listener would be nearly [MP PMT 1994; MP PET 2001] |
| A. | 1.11 f |
| B. | 1.22 f |
| C. | f |
| D. | 1.27 f |
| Answer» C. f | |
| 7674. |
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. | 1143 Hz |
| D. | 1333 Hz |
| Answer» B. 857 Hz | |
| 7675. |
The Doppler's effect is applicable for [AFMC 1998] |
| A. | Light waves |
| B. | Sound waves |
| C. | Space waves |
| D. | Both (a) and (b) |
| Answer» E. | |
| 7676. |
The wavelength is 120 cm when the source is stationary. If the source is moving with relative velocity of 60 m/sec towards the observer, then the wavelength of the sound wave reaching to the observer will be (velocity of sound = 330 m/s) |
| A. | 98 cm |
| B. | 140 cm |
| C. | 120 cm |
| D. | 144 cm |
| Answer» B. 140 cm | |
| 7677. |
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. | 150 Hz |
| D. | 100 Hz |
| Answer» B. 200 Hz | |
| 7678. |
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. | 1500 Hz |
| D. | 1600 Hz |
| Answer» E. | |
| 7679. |
A sound source is moving towards a stationary observer with 1/10 of the speed of sound. The ratio of apparent to real frequency is [CPMT 1977; NCERT 1977; KCET 2001, 03] |
| A. | 10/9 |
| B. | 11/10 |
| C. | \[{{(11/10)}^{2}}\] |
| D. | \[{{(9/10)}^{2}}\] |
| Answer» B. 11/10 | |
| 7680. |
A source of sound is travelling towards a stationary observer. The frequency of sound heard by the observer is of three times the original frequency. The velocity of sound is v m/sec. The speed of source will be [MP PET 1991] |
| A. | \[\frac{2}{3}v\] |
| B. | v |
| C. | \[\frac{3}{2}v\] |
| D. | 3v |
| Answer» B. v | |
| 7681. |
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. | 150 Hz |
| D. | 200 Hz |
| Answer» E. | |
| 7682. |
With what velocity an observer should move relative to a stationary source so that he hears a sound of double the frequency of source [MP PMT 1991] |
| A. | Velocity of sound towards the source |
| B. | Velocity of sound away from the source |
| C. | Half the velocity of sound towards the source |
| D. | Double the velocity of sound towards the source |
| Answer» B. Velocity of sound away from the source | |
| 7683. |
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. | 750 Hz |
| D. | 800 Hz |
| Answer» C. 750 Hz | |
| 7684. |
A source of sound of frequency 450 cycles/sec is moving towards a stationary observer with 34 m/sec speed. If the speed of sound is 340 m/sec, then the apparent frequency will be [MP PMT 1987] |
| A. | 410 cycles/sec |
| B. | 500 cycles/sec |
| C. | 550 cycles/sec |
| D. | 450 cycles/sec |
| Answer» C. 550 cycles/sec | |
| 7685. |
Doppler shift in frequency does not depend upon [MP PMT 1993; DPMT 2000] |
| A. | The frequency of the wave produced |
| B. | The velocity of the source |
| C. | The velocity of the observer |
| D. | Distance from the source to the listener |
| Answer» E. | |
| 7686. |
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. | 7 m/s |
| D. | 6 m/s (approx.) |
| Answer» B. 800 m/s | |
| 7687. |
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. | 300 |
| D. | 200 |
| Answer» B. 192 | |
| 7688. |
The apparent wavelength of the light from a star moving away from the earth is 0.01% more than its real wavelength. Then the velocity of star is [CPMT 1979] |
| A. | 60 km/sec |
| B. | 15 km/sec |
| C. | 150 km/sec |
| D. | 30 km/sec |
| Answer» E. | |
| 7689. |
A spectral line\[\lambda =5000\,\,{AA}\]in the light coming from a distant star is observed as a\[5200\,\,{AA}\]. What will be recession velocity of the star |
| A. | \[1.15\times {{10}^{7}}cm/\sec \] |
| B. | \[1.15\times {{10}^{7}}m/\sec \] |
| C. | \[1.15\times {{10}^{7}}km/\sec \] |
| D. | 1.15 km/sec |
| Answer» C. \[1.15\times {{10}^{7}}km/\sec \] | |
| 7690. |
A rocket is moving away from the earth at a speed of\[6\times {{10}^{7}}m/s\]. The rocket has blue light in it. What will be the wavelength of light recorded by an observer on the earth (wavelength of blue light = \[4600\,{AA}\] ) |
| A. | \[4600\,\,{AA}\] |
| B. | \[5520\,\,{AA}\] |
| C. | \[3680\,\,{AA}\] |
| D. | \[3920\,\,{AA}\] |
| Answer» C. \[3680\,\,{AA}\] | |
| 7691. |
Doppler's effect in sound in addition to relative velocity between source and observer, also depends while source and observer or both are moving. Doppler Effect in light depend only on the relative velocity of source and observer. The reason of this is [MP PET/PMT 1988] |
| A. | Einstein mass - energy relation |
| B. | Einstein theory of relativity |
| C. | Photoelectric effect |
| D. | None of these |
| Answer» C. Photoelectric effect | |
| 7692. |
It is believed that the universe is expanding and hence the distant stars are receding from us. Light from such a star will show [CPMT 2005] |
| A. | Shift in frequency towards longer wavelengths |
| B. | Shift in frequency towards shorter wavelength |
| C. | No shift in frequency but a decrease in intensity |
| D. | A shift in frequency sometimes towards longer and sometimes towards shorter wavelengths |
| Answer» B. Shift in frequency towards shorter wavelength | |
| 7693. |
Light from the constellation Virgo is observed to increase in wavelength by 0.4%. With respect to Earth the constellation is [MP PET 2003] |
| A. | Moving away with velocity 1.2 ´ 106 m/s |
| B. | Coming closer with velocity 1.2 ´ 106 m/s |
| C. | Moving away with velocity 4 ´ 106 m/s |
| D. | Coming closer with velocity 4 ´ 106 m/s |
| Answer» B. Coming closer with velocity 1.2 ´ 106 m/s | |
| 7694. |
Three observers A, B and C measure the speed of light coming from a source to be \[{{v}_{A}}\], \[{{v}_{B}}\] and \[{{v}_{C}}\]. The observer A moves towards the source, the observer C moves away from the source with the same speed. The observer B stays stationary. The surrounding space is vacuum everywhere. Then [KCET 2002] |
| A. | \[{{v}_{A}}>{{v}_{B}}>{{v}_{C}}\] |
| B. | \[{{v}_{A}}<{{v}_{B}}<{{v}_{C}}\] |
| C. | \[{{v}_{A}}={{v}_{B}}={{v}_{C}}\] |
| D. | \[{{v}_{A}}={{v}_{B}}>{{v}_{C}}\] |
| Answer» D. \[{{v}_{A}}={{v}_{B}}>{{v}_{C}}\] | |
| 7695. |
The\[6563\,\,{AA}\]line emitted by hydrogen atom in a star is found to be red shifted by\[5\,\,{AA}\]. The speed with which the star is receding from the earth is [Pb. PMT 2002] |
| A. | 17.29 - 109 m/s |
| B. | 4.29 - 107 m/s |
| C. | 3.39 - 105 m/s |
| D. | 2.29 - 105 m/s |
| Answer» E. | |
| 7696. |
A heavenly body is receding from earth such that the fractional change in l is 1, then its velocity is [DCE 2000] |
| A. | C |
| B. | \[\frac{3C}{5}\] |
| C. | \[\frac{C}{5}\] |
| D. | \[\frac{2C}{5}\] |
| Answer» B. \[\frac{3C}{5}\] | |
| 7697. |
When the wavelength of light coming from a distant star is measured it is found shifted towards red. Then the conclusion is [JIPMER 1999] |
| A. | The star is approaching the observer |
| B. | The star recedes away from earth |
| C. | There is gravitational effect on the light |
| D. | The star remains stationary |
| Answer» C. There is gravitational effect on the light | |
| 7698. |
If a star is moving towards the earth, then the lines are shifted towards [AIIMS 1997] |
| A. | Red |
| B. | Infrared |
| C. | Blue |
| D. | Green |
| Answer» D. Green | |
| 7699. |
A rocket is going away from the earth at a speed 0.2c, where c = speed of light. It emits a signal of frequency \[4\times {{10}^{7}}Hz\]. What will be the frequency observed by an observer on the earth [RPMT 1996] |
| A. | \[4\times {{10}^{6}}Hz\] |
| B. | \[3.2\times {{10}^{7}}Hz\] |
| C. | \[3\times {{10}^{6}}Hz\] |
| D. | \[5\times {{10}^{7}}Hz\] |
| Answer» C. \[3\times {{10}^{6}}Hz\] | |
| 7700. |
A rocket is going away from the earth at a speed of 106 m/s If the wavelength of the light wave emitted by it be \[5700\,\,{AA}\], what will be its Doppler's shift [RPMT 1996] |
| A. | \[200\,\,{AA}\] |
| B. | \[19\,\,{AA}\] |
| C. | \[20\,\,{AA}\] |
| D. | \[0.2\,\,{AA}\] |
| Answer» C. \[20\,\,{AA}\] | |