12583 + Mcqs in Physics Page 153 McqOptions

7601.	At a certain place, the horizontal component \[{{B}_{0}}\] and the vertical component \[{{V}_{0}}\] of the earth's magnetic field are equal in magnitude. The total intensity at the place will be [MP PMT 1999, 2003]
A.	\[{{B}_{0}}\]
B.	\[B_{0}^{2}\]
C.	\[2{{B}_{0}}\]
D.	\[\sqrt{2}{{B}_{0}}\]
Answer» E.

Discussion

7602.	Lines which represent places of constant angle of dip are called
A.	Isobaric lines
B.	Isogonic lines
C.	Isoclinic lines
D.	Isodynamic lines
Answer» D. Isodynamic lines

Discussion

7603.	When the N-pole of a bar magnet points towards the south and S-pole towards the north, the null points are at the [MP PMT 1996]
A.	Magnetic axis
B.	Magnetic centre
C.	Perpendicular divider of magnetic axis
D.	N and S poles
Answer» B. Magnetic centre

Discussion

7604.	The value of the horizontal component of the earth's magnetic field and angle of dip are \[1.8\times {{10}^{-5}}Weber/{{m}^{2}}\] and 30° respectively at some place. The total intensity of earth's magnetic field at that place will be [MP PET 1996]
A.	\[2.08\times {{10}^{-5}}Weber/{{m}^{2}}\]
B.	\[3.67\times {{10}^{-5}}Weber/{{m}^{2}}\]
C.	\[3.18\times {{10}^{-5}}Weber/{{m}^{2}}\]
D.	\[5.0\times {{10}^{-5}}Weber/{{m}^{2}}\]
Answer» B. \[3.67\times {{10}^{-5}}Weber/{{m}^{2}}\]

Discussion

7605.	The magnetic field due to the earth is closely equivalent to that due to [BIT Ranchi 1982]
A.	A large magnet of length equal to the diameter of the earth
B.	A magnetic dipole placed at the centre of the earth
C.	A large coil carrying current
D.	Neither of the above
Answer» B. A magnetic dipole placed at the centre of the earth

Discussion

7606.	The earth's magnetic field at a certain place has a horizontal component 0.3 Gauss and the total strength 0.5 Gauss. The angle of dip is [MP PMT 1995]
A.	\[{{\tan }^{-1}}\frac{3}{4}\]
B.	\[{{\sin }^{-1}}\frac{3}{4}\]
C.	\[{{\tan }^{-1}}\frac{4}{3}\]
D.	\[{{\sin }^{-1}}\frac{3}{5}\]
Answer» D. \[{{\sin }^{-1}}\frac{3}{5}\]

Discussion

7607.	In two separate experiments the neutral points due to two small magnets are at a distance of r and 2r in broad side-on position. The ratio of their magnetic moments will be [MP PMT 1985]
A.	4 : 1
B.	1 : 2
C.	2 : 1
D.	1 : 8
Answer» E.

Discussion

7608.	A bar magnet is placed north-south with its north pole due north. The points of zero magnetic field will be in which direction from the centre of the magnet [MNR 1995; MP PMT 1995; UPSEAT 2000]
A.	North and south
B.	East and west
C.	North-east and south-west
D.	North-west and south-east
Answer» C. North-east and south-west

Discussion

7609.	Earth's magnetic field always has a horizontal component except at or Horizontal component of earth's magnetic field remains zero at [CPMT 1971, 81, 83]
A.	Equator
B.	Magnetic poles
C.	A latitude of 60o
D.	An altitude of 60o
Answer» C. A latitude of 60o

Discussion

7610.	A dip circle is at right angle to the magnetic meridian. What will be the apparent dip [AFMC 1995]
A.	0°
B.	30°
C.	60º
D.	90°
Answer» E.

Discussion

7611.	At a place, the magnitudes of the horizontal component and total intensity of the magnetic field of the earth are 0.3 and 0.6 Oersted respectively. The value of the angle of dip at this place will be [MP PMT 1994]
A.	60°
B.	45°
C.	30°
D.	0°
Answer» B. 45°

Discussion

7612.	At the magnetic north pole of the earth, the value of horizontal component of earth's magnetic field and angle of dip are, respectively [MP PMT 1994]
A.	Zero, maximum
B.	Maximum, minimum
C.	Maximum, maximum
D.	Minimum, minimum
Answer» B. Maximum, minimum

Discussion

7613.	The angle of dip at a place on the earth gives [MP PET 1994]
A.	The horizontal component of the earth's magnetic field
B.	The location of the geographic meridian
C.	The vertical component of the earth's field
D.	The direction of the earth's magnetic field
Answer» E.

Discussion

7614.	The magnetic compass is not useful for navigation near the magnetic poles because [BIT Ranchi 1982]
A.	The magnetic field near the poles is zero
B.	The magnetic field near the poles is almost vertical
C.	At low temperature, the compass needle looses its magnetic properties
D.	Neither of the above
Answer» C. At low temperature, the compass needle looses its magnetic properties

Discussion

7615.	The angle of dip at a place is 60°. At this place the total intensity of earth's magnetic field is 0.64 units. The horizontal intensity of earth's magnetic field at this place is [MP PET 1984]
A.	1.28 units
B.	0.64 units
C.	0.16 units
D.	0.32 units
Answer» E.

Discussion

7616.	At a place, the horizontal and vertical intensities of earth's magnetic field is 0.30 Gauss and 0.173 Gauss respectively. The angle of dip at this place is [MP PMT 1986]
A.	30°
B.	90°
C.	60°
D.	45°
Answer» B. 90°

Discussion

7617.	Ratio between total intensity of magnetic field at equator to poles is [IIT 1970; CPMT 1981]
A.	1 : 1
B.	1 : 2
C.	2 : 1
D.	1 : 4
Answer» C. 2 : 1

Discussion

7618.	A line passing through places having zero value of magnetic dip is called [CPMT 1987]
A.	Isoclinic line
B.	Agonic line
C.	Isogonic line
D.	Aclinic line
Answer» E.

Discussion

7619.	The lines joining the places of the same horizontal intensity are known as [MNR 1984]
A.	Isogonic lines
B.	Aclinic lines
C.	Isoclinic lines
D.	Agonic lines
E.	(e) Isodynamic lines
Answer» F.

Discussion

7620.	The angle between the earth's magnetic and the earth's geographical axes is [MNR 1979]
A.	Zero
B.	17°
C.	23°
D.	None of these
Answer» C. 23°

Discussion

7621.	Intensity of magnetic field due to earth at a point inside a hollow steel box is [MP PET 1995]
A.	Less than outside
B.	More than outside
C.	Same
D.	Zero
Answer» E.

Discussion

7622.	The line on the earth's surface joining the points where the field is horizontal is [MNR 1985; UPSEAT 1999; Pb PET 2004]
A.	Magnetic meridian
B.	Magnetic axis
C.	Magnetic line
D.	Magnetic equator
E.	(e) Isogonic line
Answer» E. (e) Isogonic line

Discussion

7623.	The angle of dip at the magnetic equator is [MP PET 1984; MP PMT 1987; CBSE PMT 1989, 90; MP Board 1980; CPMT 1977, 87, 90; Manipal MEE 1995]
A.	0°
B.	45°
C.	30°
D.	90°
Answer» B. 45°

Discussion

7624.	At a certain place the angle of dip is 30° and the horizontal component of earth's magnetic field is 0.50 Oersted. The earth's total magnetic field is [CPMT 1990]
A.	\[\sqrt{3}\]
B.	\[1\]
C.	\[\frac{1}{\sqrt{3}}\]
D.	\[\frac{1}{2}\]
Answer» D. \[\frac{1}{2}\]

Discussion

7625.	The angle of dip at a place is 40.6o and the intensity of the vertical component of the earth's magnetic field \[V=6\times {{10}^{-5}}\]Tesla. The total intensity of the earth's magnetic field (I) at this place is [MP PMT 1993]
A.	\[7\times {{10}^{-5}}tesla\]
B.	\[6\times {{10}^{-5}}tesla\]
C.	\[5\times {{10}^{-5}}tesla\]
D.	\[9.2\times {{10}^{-5}}tesla\]
Answer» E.

Discussion

7626.	The angle of dip is the angle [CPMT 1978]
A.	Between the vertical component of earth's magnetic field and magnetic meridian
B.	Between the vertical component of earth's magnetic field and geographical meridian
C.	Between the earth's magnetic field direction and horizontal direction
D.	Between the magnetic meridian and the geographical meridian
Answer» D. Between the magnetic meridian and the geographical meridian

Discussion

7627.	At a place the earth's horizontal component of magnetic field is \[0.36\times {{10}^{-4}}weber/{{m}^{2}}\]. If the angle of dip at that place is 60o, then the vertical component of earth's field at that place in weber/m2 will be approximately [MP PMT 1985]
A.	\[0.12\times {{10}^{-4}}\]
B.	\[0.24\times {{10}^{-4}}\]
C.	\[0.40\times {{10}^{-4}}\]
D.	\[0.62\times {{10}^{-4}}\]
Answer» E.

Discussion

7628.	If the angles of dip at two places are 30o and 45o respectively, then the ratio of horizontal components of earth's magnetic field at the two places will be [MP PET 1989]
A.	\[\sqrt{3}:\sqrt{2}\]
B.	\[1:\sqrt{2}\]
C.	\[1:\sqrt{3}\]
D.	\[1:2\]
Answer» B. \[1:\sqrt{2}\]

Discussion

7629.	At a place, if the earth's horizontal and vertical components of magnetic fields are equal, then the angle of dip will be [SCRA 1994; DCE 2001; MP PMT 2002]
A.	\[30{}^\circ \]
B.	\[90{}^\circ \]
C.	\[45{}^\circ \]
D.	0°
Answer» D. 0°

Discussion

7630.	The lines of forces due to earth's horizontal component of magnetic field are [CPMT 1985; MP PMT 1980; AIIMS 1998]
A.	Parallel straight lines
B.	Concentric circles
C.	Elliptical
D.	Parabolic
Answer» B. Concentric circles

Discussion

7631.	A very small magnet is placed in the magnetic meridian with its south pole pointing north. The null point is obtained 20 cm away from the centre of the magnet. If the earth's magnetic field (horizontal component) at this point be 0.3 gauss, the magnetic moment of the magnet is [CPMT 1987; MNR 1978]
A.	\[8.0\times {{10}^{2}}e.m.u.\]
B.	\[1.2\times {{10}^{3}}e.m.u.\]
C.	\[2.4\times {{10}^{3}}e.m.u.\]
D.	\[3.6\times {{10}^{3}}e.m.u.\]
Answer» C. \[2.4\times {{10}^{3}}e.m.u.\]

Discussion

7632.	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.	Apparent frequency will be equal to real frequency
D.	Only the quality of sound will change
Answer» C. Apparent frequency will be equal to real frequency

Discussion

7633.	An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency [AIEEE 2005]
A.	5%
B.	20%
C.	Zero
D.	0.5%
Answer» C. Zero

Discussion

7634.	The apparent frequency of a note, when a listener moves towards a stationary source, with velocity of 40 m/s is 200 Hz. When he moves away from the same source with the same speed, the apparent frequency of the same note is 160 Hz. The velocity of sound in air is (in m/s) [KCET 1998]
A.	360
B.	330
C.	320
D.	340
Answer» B. 330

Discussion

7635.	A source of sound of frequency 256 Hz is moving rapidly towards a wall with a velocity of 5m/s. The speed of sound is 330 m/s. If the observer is between the wall and the source, then beats per second heard will be [UPSEAT 2002]
A.	7.8 Hz
B.	7.7 Hz
C.	3.9 Hz
D.	Zero
Answer» B. 7.7 Hz

Discussion

7636.	A bus is moving with a velocity of 5 m/s towards a huge wall. the driver sounds a horn of frequency 165 Hz. If the speed of sound in air is 355 m/s, the number of beats heard per second by a passenger on the bus will be [KCET 2001; BHU 2002]
A.	6
B.	5
C.	3
D.	4
Answer» C. 3

Discussion

7637.	A person carrying a whistle emitting continuously a note of 272 Hz is running towards a reflecting surface with a speed of 18 km/hour. The speed of sound in air is \[345m{{s}^{-1}}\]. The number of beats heard by him is [Kerala (Engg.) 2002]
A.	4
B.	6
C.	8
D.	3
Answer» D. 3

Discussion

7638.	An observer moves towards a stationary source of sound of frequency n. The apparent frequency heard by him is 2n. If the velocity of sound in air is 332 m/sec, then the velocity of the observer is [MP PET 1990]
A.	166 m/sec
B.	664 m/sec
C.	332 m/sec
D.	1328 m/sec
Answer» D. 1328 m/sec

Discussion

7639.	A police car horn emits a sound at a frequency 240 Hz when the car is at rest. If the speed of the sound is 330 m/s, the frequency heard by an observer who is approaching the car at a speed of 11 m/s, is : [UPSEAT 2004]
A.	248 Hz
B.	244 Hz
C.	240 Hz
D.	230 Hz
Answer» B. 244 Hz

Discussion

7640.	When an engine passes near to a stationary observer then its apparent frequencies occurs in the ratio 5/3. If the velocity of engine is [MP PMT 2003]
A.	540 m/s
B.	270 m/s
C.	85 m/s
D.	52.5 m/s
Answer» D. 52.5 m/s

Discussion

7641.	A source and an observer are moving towards each other with a speed equal to \[\frac{v}{2}\] where \[v\] is the speed of sound. The source is emitting sound of frequency n. The frequency heard by the observer will be [MP PET 2003]
A.	Zero
B.	\[n\]
C.	\[\frac{n}{3}\]
D.	\[3n\]
Answer» E.

Discussion

7642.	Doppler effect is applicable for [AFMC 2003]
A.	Moving bodies
B.	One is moving and other are stationary
C.	For relative motion
D.	None of these
Answer» D. None of these

Discussion

7643.	A source emits a sound of frequency of 400 Hz, but the listener hears it to be 390 Hz. Then [Orissa JEE 2003]
A.	The listener is moving towards the source
B.	The source is moving towards the listener
C.	The listener is moving away from the source
D.	The listener has a defective ear
Answer» D. The listener has a defective ear

Discussion

7644.	A source and an observer approach each other with same velocity 50 m/s. If the apparent frequency is 435 sec?1, then the real frequency is [CPMT 2003]
A.	320 s?1
B.	360 sec?1
C.	390 sec?1
D.	420 sec?1
Answer» B. 360 sec?1

Discussion

7645.	A small source of sound moves on a circle as shown in the figure and an observer is standing on \[O\]. Let \[{{n}_{1}},\ {{n}_{2}}\] and \[{{n}_{3}}\]be the frequencies heard when the source is at \[A,\ B\] and \[C\] respectively. Then [UPSEAT 2002]
A.	\[{{n}_{1}}>{{n}_{2}}>{{n}_{3}}\]
B.	\[{{n}_{2}}>{{n}_{3}}>{{n}_{1}}\]
C.	\[{{n}_{1}}={{n}_{2}}>{{n}_{3}}\]
D.	\[{{n}_{2}}>{{n}_{1}}>{{n}_{3}}\]
Answer» C. \[{{n}_{1}}={{n}_{2}}>{{n}_{3}}\]

Discussion

7646.	Two trains are moving towards each other at speeds of 20 m/s and 15 m/s relative to the ground. The first train sounds a whistle of frequency 600 Hz. the frequency of the whistle heard by a passenger in the second train before the train meets is (the speed of sound in air is 340 m/s) [UPSEAT 2002]
A.	600 Hz
B.	585 Hz
C.	645 Hz
D.	666 Hz
Answer» E.

Discussion

7647.	What should be the velocity of a sound source moving towards a stationary observer so that apparent frequency is double the actual frequency (Velocity of sound is v) [MP PMT 2002]
A.	v
B.	2v
C.	\[\frac{v}{2}\]
D.	\[\frac{v}{4}\]
Answer» D. \[\frac{v}{4}\]

Discussion

7648.	A car sounding a horn of frequency 1000 Hz passes an observer. The ratio of frequencies of the horn noted by the observer before and after passing of the car is 11 : 9. If the speed of sound is v, the speed of the car is [MP PET 2002]
A.	\[\frac{1}{10}v\]
B.	\[\frac{1}{2}v\]
C.	\[\frac{1}{5}v\]
D.	v
Answer» B. \[\frac{1}{2}v\]

Discussion

7649.	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) [MP PMT 1989]
A.	\[\frac{n(v+{{v}_{o}})}{v-{{v}_{o}}}\]
B.	\[\frac{n(v-{{v}_{o}})}{v-{{v}_{s}}}\]
C.	\[\frac{n(v-{{v}_{o}})}{v+{{v}_{s}}}\]
D.	\[\frac{n(v+{{v}_{o}})}{v+{{v}_{s}}}\]
Answer» C. \[\frac{n(v-{{v}_{o}})}{v+{{v}_{s}}}\]

Discussion

7650.	A Siren emitting sound of frequency 800 Hz is going away from a static listener with a speed of 30 m/s, frequency of the sound to be heard by the listener is (take velocity of sound as 330 m/s) [CPMT 1996; AIIMS 2002; Pb. PMT 2001]
A.	733.3 Hz
B.	644.8 Hz
C.	481.2 Hz
D.	286.5 Hz
Answer» B. 644.8 Hz

Discussion

Explore topic-wise MCQs in Joint Entrance Exam - Main (JEE Main).

At a certain place, the horizontal component \[{{B}_{0}}\] and the vertical component \[{{V}_{0}}\] of the earth's magnetic field are equal in magnitude. The total intensity at the place will be [MP PMT 1999, 2003]

Lines which represent places of constant angle of dip are called

When the N-pole of a bar magnet points towards the south and S-pole towards the north, the null points are at the [MP PMT 1996]

The value of the horizontal component of the earth's magnetic field and angle of dip are \[1.8\times {{10}^{-5}}Weber/{{m}^{2}}\] and 30° respectively at some place. The total intensity of earth's magnetic field at that place will be [MP PET 1996]

The magnetic field due to the earth is closely equivalent to that due to [BIT Ranchi 1982]

The earth's magnetic field at a certain place has a horizontal component 0.3 Gauss and the total strength 0.5 Gauss. The angle of dip is [MP PMT 1995]

In two separate experiments the neutral points due to two small magnets are at a distance of r and 2r in broad side-on position. The ratio of their magnetic moments will be [MP PMT 1985]

A bar magnet is placed north-south with its north pole due north. The points of zero magnetic field will be in which direction from the centre of the magnet [MNR 1995; MP PMT 1995; UPSEAT 2000]

Earth's magnetic field always has a horizontal component except at or Horizontal component of earth's magnetic field remains zero at [CPMT 1971, 81, 83]

A dip circle is at right angle to the magnetic meridian. What will be the apparent dip [AFMC 1995]

At a place, the magnitudes of the horizontal component and total intensity of the magnetic field of the earth are 0.3 and 0.6 Oersted respectively. The value of the angle of dip at this place will be [MP PMT 1994]

At the magnetic north pole of the earth, the value of horizontal component of earth's magnetic field and angle of dip are, respectively [MP PMT 1994]

The angle of dip at a place on the earth gives [MP PET 1994]

The magnetic compass is not useful for navigation near the magnetic poles because [BIT Ranchi 1982]

The angle of dip at a place is 60°. At this place the total intensity of earth's magnetic field is 0.64 units. The horizontal intensity of earth's magnetic field at this place is [MP PET 1984]

At a place, the horizontal and vertical intensities of earth's magnetic field is 0.30 Gauss and 0.173 Gauss respectively. The angle of dip at this place is [MP PMT 1986]

Ratio between total intensity of magnetic field at equator to poles is [IIT 1970; CPMT 1981]

A line passing through places having zero value of magnetic dip is called [CPMT 1987]

The lines joining the places of the same horizontal intensity are known as [MNR 1984]

The angle between the earth's magnetic and the earth's geographical axes is [MNR 1979]

Intensity of magnetic field due to earth at a point inside a hollow steel box is [MP PET 1995]

The line on the earth's surface joining the points where the field is horizontal is [MNR 1985; UPSEAT 1999; Pb PET 2004]

The angle of dip at the magnetic equator is [MP PET 1984; MP PMT 1987; CBSE PMT 1989, 90; MP Board 1980; CPMT 1977, 87, 90; Manipal MEE 1995]

At a certain place the angle of dip is 30° and the horizontal component of earth's magnetic field is 0.50 Oersted. The earth's total magnetic field is [CPMT 1990]

The angle of dip at a place is 40.6o and the intensity of the vertical component of the earth's magnetic field \[V=6\times {{10}^{-5}}\]Tesla. The total intensity of the earth's magnetic field (I) at this place is [MP PMT 1993]

The angle of dip is the angle [CPMT 1978]

At a place the earth's horizontal component of magnetic field is \[0.36\times {{10}^{-4}}weber/{{m}^{2}}\]. If the angle of dip at that place is 60o, then the vertical component of earth's field at that place in weber/m2 will be approximately [MP PMT 1985]

If the angles of dip at two places are 30o and 45o respectively, then the ratio of horizontal components of earth's magnetic field at the two places will be [MP PET 1989]

At a place, if the earth's horizontal and vertical components of magnetic fields are equal, then the angle of dip will be [SCRA 1994; DCE 2001; MP PMT 2002]

The lines of forces due to earth's horizontal component of magnetic field are [CPMT 1985; MP PMT 1980; AIIMS 1998]

A very small magnet is placed in the magnetic meridian with its south pole pointing north. The null point is obtained 20 cm away from the centre of the magnet. If the earth's magnetic field (horizontal component) at this point be 0.3 gauss, the magnetic moment of the magnet is [CPMT 1987; MNR 1978]

An observer is moving towards the stationary source of sound, then [MH CET 2001]

An observer moves towards a stationary source of sound, with a velocity one-fifth of the velocity of sound. What is the percentage increase in the apparent frequency [AIEEE 2005]

The apparent frequency of a note, when a listener moves towards a stationary source, with velocity of 40 m/s is 200 Hz. When he moves away from the same source with the same speed, the apparent frequency of the same note is 160 Hz. The velocity of sound in air is (in m/s) [KCET 1998]

A source of sound of frequency 256 Hz is moving rapidly towards a wall with a velocity of 5m/s. The speed of sound is 330 m/s. If the observer is between the wall and the source, then beats per second heard will be [UPSEAT 2002]

A bus is moving with a velocity of 5 m/s towards a huge wall. the driver sounds a horn of frequency 165 Hz. If the speed of sound in air is 355 m/s, the number of beats heard per second by a passenger on the bus will be [KCET 2001; BHU 2002]

A person carrying a whistle emitting continuously a note of 272 Hz is running towards a reflecting surface with a speed of 18 km/hour. The speed of sound in air is \[345m{{s}^{-1}}\]. The number of beats heard by him is [Kerala (Engg.) 2002]

An observer moves towards a stationary source of sound of frequency n. The apparent frequency heard by him is 2n. If the velocity of sound in air is 332 m/sec, then the velocity of the observer is [MP PET 1990]

A police car horn emits a sound at a frequency 240 Hz when the car is at rest. If the speed of the sound is 330 m/s, the frequency heard by an observer who is approaching the car at a speed of 11 m/s, is : [UPSEAT 2004]

When an engine passes near to a stationary observer then its apparent frequencies occurs in the ratio 5/3. If the velocity of engine is [MP PMT 2003]

A source and an observer are moving towards each other with a speed equal to \[\frac{v}{2}\] where \[v\] is the speed of sound. The source is emitting sound of frequency n. The frequency heard by the observer will be [MP PET 2003]

Doppler effect is applicable for [AFMC 2003]

A source emits a sound of frequency of 400 Hz, but the listener hears it to be 390 Hz. Then [Orissa JEE 2003]

A source and an observer approach each other with same velocity 50 m/s. If the apparent frequency is 435 sec?1, then the real frequency is [CPMT 2003]

A small source of sound moves on a circle as shown in the figure and an observer is standing on \[O\]. Let \[{{n}_{1}},\ {{n}_{2}}\] and \[{{n}_{3}}\]be the frequencies heard when the source is at \[A,\ B\] and \[C\] respectively. Then [UPSEAT 2002]

Two trains are moving towards each other at speeds of 20 m/s and 15 m/s relative to the ground. The first train sounds a whistle of frequency 600 Hz. the frequency of the whistle heard by a passenger in the second train before the train meets is (the speed of sound in air is 340 m/s) [UPSEAT 2002]

What should be the velocity of a sound source moving towards a stationary observer so that apparent frequency is double the actual frequency (Velocity of sound is v) [MP PMT 2002]

A car sounding a horn of frequency 1000 Hz passes an observer. The ratio of frequencies of the horn noted by the observer before and after passing of the car is 11 : 9. If the speed of sound is v, the speed of the car is [MP PET 2002]

A Siren emitting sound of frequency 800 Hz is going away from a static listener with a speed of 30 m/s, frequency of the sound to be heard by the listener is (take velocity of sound as 330 m/s) [CPMT 1996; AIIMS 2002; Pb. PMT 2001]