MCQOPTIONS
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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.
| 5551. |
Two tangent galvanometers having coils of the same radius are connected in series. A current flowing in them produces deflections of 60° and 45° respectively. The ratio of the number of turns in the coils is [MP PET 1995; MP PMT 1999] |
| A. | 4/3 |
| B. | \[(\sqrt{3}+1)/1\] |
| C. | \[(\sqrt{3}+1)/(\sqrt{3}-1)\] |
| D. | \[\sqrt{3}/1\] |
| Answer» E. | |
| 5552. |
The sensitivity of a tangent galvanometer is increased if [AFMC 1995] |
| A. | Number of turn decreases |
| B. | Number of turn increases |
| C. | Field increases |
| D. | None of the above |
| Answer» C. Field increases | |
| 5553. |
A magnetic needle suspended by a silk thread is vibrating in the earth's magnetic field. If the temperature of the needle is increased by 500°C, then [MNR 1994] |
| A. | The time period decreases |
| B. | The time period remains unchanged |
| C. | The time period increases |
| D. | The needle stops vibrating |
| Answer» D. The needle stops vibrating | |
| 5554. |
The number of turns and radius of cross-section of the coil of a tangent galvanometer are doubled. The reduction factor K will be [NCERT 1983; MP PMT 2002] |
| A. | K |
| B. | 2K |
| C. | 4K |
| D. | K/4 |
| Answer» B. 2K | |
| 5555. |
Which of the following statement is true about magnetic moments of atoms of different elements [CPMT 1977] |
| A. | All have a magnetic moment |
| B. | None has a magnetic moment |
| C. | All acquire a magnetic moment under external magnetic field and in same direction as the field |
| D. | None of the above statements are accurate |
| Answer» E. | |
| 5556. |
The time period of a freely suspended magnet is 4 seconds. If it is broken in length into two equal parts and one part is suspended in the same way, then its time period will be [NCERT 1984; CPMT 1991; MP PMT 1994; MH CET 2004] |
| A. | 4 sec |
| B. | 2 sec |
| C. | 0.5 sec |
| D. | 0.25 sec |
| Answer» C. 0.5 sec | |
| 5557. |
A bar magnet has a magnetic moment equal to\[5\times {{10}^{-5}}weber\times m.\] It is suspended in a magnetic field which has a magnetic induction equal to \[8\pi \times {{10}^{-4}}tesla.\] The magnet vibrates with a period of vibration equal to 15 sec. The moment of inertia of the magnet is [MP PMT 1993; CBSE PMT 2001] |
| A. | \[22.5kg\times {{m}^{2}}\] |
| B. | \[11.25\times kg\times {{m}^{2}}\] |
| C. | \[5.62\times kg\times {{m}^{2}}\] |
| D. | \[7.16\times {{10}^{-7}}kg-{{m}^{2}}\] |
| Answer» E. | |
| 5558. |
A tangent galvanometer has a coil with 50 turns and radius equal to 4 cm. A current of 0.1 A is passing through it. The plane of the coil is set parallel to the earth's magnetic meridian. If the value of the earth's horizontal component of the magnetic field is \[7\times {{10}^{-5}}\]tesla and\[{{\mu }_{0}}=4\pi \times {{10}^{-7}}weber/amp\times m\], then the deflection in the galvanometer needle will be [MP PMT 1993] |
| A. | 45o |
| B. | 48.2o |
| C. | 50.7o |
| D. | 52.7o |
| Answer» C. 50.7o | |
| 5559. |
Tangent galvanometer is used to measure [MP PET 1993] |
| A. | Steady currents |
| B. | Current impulses |
| C. | Magnetic moments of bar magnets |
| D. | Earth's magnetic field |
| Answer» B. Current impulses | |
| 5560. |
The time period of oscillation of a freely suspended bar magnet with usual notations is given by [CPMT 1973, 76, 87; MP PET 1994, 96] |
| A. | \[T=2\pi \sqrt{\frac{I}{M{{B}_{H}}}}\] |
| B. | \[T=2\pi \sqrt{\frac{M{{B}_{H}}}{I}}\] |
| C. | \[T=\sqrt{\frac{I}{M{{B}_{H}}}}\] |
| D. | \[T=2\pi \sqrt{\frac{{{B}_{H}}}{MI}}\] |
| Answer» B. \[T=2\pi \sqrt{\frac{M{{B}_{H}}}{I}}\] | |
| 5561. |
Vibration magnetometer works on the principle of [MP PET 1993] |
| A. | Torque acting on the bar magnet |
| B. | Force acting on the bar magnet |
| C. | Both the force and the torque acting on the bar magnet |
| D. | None of these |
| Answer» B. Force acting on the bar magnet | |
| 5562. |
A small bar magnet A oscillates in a horizontal plane with a period T at a place where the angle of dip is 60o. When the same needle is made to oscillate in a vertical plane coinciding with the magnetic meridian, its period will be [MP PMT 1992] |
| A. | \[\frac{T}{\sqrt{2}}\] |
| B. | \[T\] |
| C. | \[\sqrt{2}T\] |
| D. | \[2T\] |
| Answer» B. \[T\] | |
| 5563. |
Magnets A and B are geometrically similar but the magnetic moment of A is twice that of B. If T1 and T2 be the time periods of the oscillation when their like poles and unlike poles are kept together respectively, then \[\frac{{{T}_{1}}}{{{T}_{2}}}\]will be [SCRA 1998] |
| A. | \[\frac{1}{3}\] |
| B. | \[\frac{1}{2}\] |
| C. | \[\frac{1}{\sqrt{3}}\] |
| D. | \[\sqrt{3}\] |
| Answer» D. \[\sqrt{3}\] | |
| 5564. |
The time period of a bar magnet suspended horizontally in the earth's magnetic field and allowed to oscillate [MP PET 1992] |
| A. | Is directly proportional to the square root of its mass |
| B. | Is directly proportional to its pole strength |
| C. | Is inversely proportional to its magnetic moment |
| D. | Decreases if the length increases but pole strength remains same |
| Answer» B. Is directly proportional to its pole strength | |
| 5565. |
At two places A and B using vibration magnetometer, a magnet vibrates in a horizontal plane and its respective periodic time are 2 sec and 3 sec and at these places the earth's horizontal components are HA and HB respectively. Then the ratio between HA and HB will be [MP PMT 1985, 89] |
| A. | 9 : 4 |
| B. | 3 : 2 |
| C. | 4 : 9 |
| D. | 2 : 3 |
| Answer» B. 3 : 2 | |
| 5566. |
A magnetic needle suspended horizontally by an unspun silk fibre, oscillates in the horizontal plane because of the restoring force originating mainly from [CPMT 1980, 89] |
| A. | The torsion of the silk fibre |
| B. | The force of gravity |
| C. | The horizontal component of earth's magnetic field |
| D. | All the above factors |
| Answer» D. All the above factors | |
| 5567. |
A magnet of magnetic moment M oscillating freely in earth's horizontal magnetic field makes n oscillations per minute. If the magnetic moment is quadrupled and the earth's field is doubled, the number of oscillations made per minute would be [MP PET 1991] |
| A. | \[\frac{n}{2\sqrt{2}}\] |
| B. | \[\frac{n}{\sqrt{2}}\] |
| C. | \[2\sqrt{2}n\] |
| D. | \[\sqrt{2}n\] |
| Answer» D. \[\sqrt{2}n\] | |
| 5568. |
Two magnets A and B are identical in mass, length and breadth but have different magnetic moments. In a vibration magnetometer, if the time period of B is twice the time period of A. The ratio of the magnetic moments \[{{M}_{A}}/{{M}_{B}}\] of the magnets will be [MP PET 1990; MP PMT 1990] |
| A. | \[1/2\] |
| B. | \[2\] |
| C. | \[4\] |
| D. | \[1/4\] |
| Answer» D. \[1/4\] | |
| 5569. |
A bar magnet A of magnetic moment MA is found to oscillate at a frequency twice that of magnet B of magnetic moment MB when placed in a vibrating magneto-meter. We may say that [MP PMT 1991] |
| A. | \[{{M}_{A}}=2{{M}_{B}}\] |
| B. | \[{{M}_{A}}=8{{M}_{B}}\] |
| C. | \[{{M}_{A}}=4{{M}_{B}}\] |
| D. | \[{{M}_{B}}=8{{M}_{A}}\] |
| Answer» D. \[{{M}_{B}}=8{{M}_{A}}\] | |
| 5570. |
The time period of oscillation of a magnet in a vibration magnetometer is 1.5 seconds. The time period of oscillation of another magnet similar in size, shape and mass but having one-fourth magnetic moment than that of first magnet, oscillating at same place will be [MP PMT 1991; MP PMT 2002] |
| A. | 0.75 sec |
| B. | 1.5 sec |
| C. | 3 sec |
| D. | 6 sec |
| Answer» D. 6 sec | |
| 5571. |
Magnetic moments of two bar magnets may be compared with the help of [MP PET/PMT 1988] |
| A. | Deflection magnetometer |
| B. | Vibration magnetometer |
| C. | Both of the above |
| D. | None of the above |
| Answer» D. None of the above | |
| 5572. |
A magnet is suspended in such a way that it oscillates in the horizontal plane. It makes 20 oscillations per minute at a place where dip angle is 30o and 15 oscillations per minute at a place where dip angle is 60o. The ratio of total earth's magnetic field at the two places is [MP PMT 1991; BHU 1997] |
| A. | \[3\sqrt{3}:8\] |
| B. | \[16:9\sqrt{3}\] |
| C. | \[4:9\] |
| D. | \[2\sqrt{3}:9\] |
| Answer» C. \[4:9\] | |
| 5573. |
To compare magnetic moments of two magnets by vibration magnetometer, 'sum and difference method' is better because |
| A. | Determination of moment of inertia is not needed which minimises the errors |
| B. | Less observations are required |
| C. | Comparatively less calculations |
| D. | All the above |
| Answer» E. | |
| 5574. |
Two bar magnets of the same mass, length and breadth but magnetic moments M and 2M respectively, when placed in same position, time period is 3 sec. What will be the time period when they are placed in different position [NCERT 1977; DPMT 1999] |
| A. | \[\sqrt{3}\sec \] |
| B. | \[3\sqrt{3}\sec \] |
| C. | \[3\sec \] |
| D. | \[6\sec \] |
| Answer» C. \[3\sec \] | |
| 5575. |
A magnetic needle is made to vibrate in uniform field H, then its time period is T. If it vibrates in the field of intensity 4H, its time period will be [MP Board 1988; MP PMT 1992; MH CET (Med.) 1999] |
| A. | \[2T\] |
| B. | \[T/2\] |
| C. | \[2/T\] |
| D. | \[T\] |
| Answer» C. \[2/T\] | |
| 5576. |
If a brass bar is placed on a vibrating magnet, then its time period |
| A. | Decreases |
| B. | Increases |
| C. | Remains unchanged |
| D. | First increases then decreases |
| Answer» C. Remains unchanged | |
| 5577. |
Vibration magnetometer before use, should be set |
| A. | In magnetic meridian |
| B. | In geographical meridian |
| C. | Perpendicular to magnetic meridian |
| D. | In any position |
| Answer» B. In geographical meridian | |
| 5578. |
The period of oscillation of a magnet in vibration magnetometer is 2 sec. The period of oscillation of a magnet whose magnetic moment is four times that of the first magnet is [CPMT 1975, 77, 79, 89, 90; MP PMT 1986] |
| A. | 1 sec |
| B. | 4 sec |
| C. | 8 sec |
| D. | 0.5 sec |
| Answer» B. 4 sec | |
| 5579. |
Moment of inertia of a magnetic needle is 40 gm-cm2 has time period 3 seconds in earth's horizontal field = \[3.6\times {{10}^{-5}}\]weber/m2. Its magnetic moment will be |
| A. | \[0.5\,A\times {{m}^{2}}\] |
| B. | \[5\,A\times {{m}^{2}}\] |
| C. | \[0.250\,A\times {{m}^{2}}\] |
| D. | \[5\times {{10}^{2}}A\times {{m}^{2}}\] |
| Answer» B. \[5\,A\times {{m}^{2}}\] | |
| 5580. |
Twists of suspension fibre should be removed in vibration magnetometer so that |
| A. | Time period be less |
| B. | Time period be more |
| C. | Magnet may vibrate freely |
| D. | Cannot be said with certainty |
| Answer» D. Cannot be said with certainty | |
| 5581. |
Time period in vibration magnetometer will be infinity at |
| A. | Magnetic equator |
| B. | Magnetic poles |
| C. | Equator |
| D. | At all places |
| Answer» C. Equator | |
| 5582. |
Time period of a freely suspended magnet does not depend upon [NCERT 1980; CPMT 1980; MP PET 1997] |
| A. | Length of the magnet |
| B. | Pole strength of the magnet |
| C. | Horizontal component of earth's magnetic field |
| D. | Length of the suspension thread |
| Answer» E. | |
| 5583. |
A magnet of length 0.1 m and pole strength \[{{10}^{-4}}A.m.\] is kept in a magnetic field of \[30\,Wb/{{m}^{2}}\] at an angle 30°. The couple acting on it is ??? \[\times {{10}^{-4}}Nm.\] [MP PET 2005] |
| A. | 7.5 |
| B. | 3.0 |
| C. | 1.5 |
| D. | 6.0 |
| Answer» D. 6.0 | |
| 5584. |
Two identical short bar magnets, each having magnetic moment of 10 Am2, are arranged such that their axial lines are perpendicular to each other and their centres be along the same straight line in a horizontal plane. If the distance between their centres is 0.2 m, the resultant magnetic induction at a point midway between them is \[({{\mu }_{0}}=4\pi \times {{10}^{-7}}H{{m}^{-1}})\] [EAMCET 2005] |
| A. | \[\sqrt{2}\times {{10}^{-7}}\] Tesla |
| B. | \[\sqrt{5}\times {{10}^{-7}}\] Tesla |
| C. | \[\sqrt{2}\times {{10}^{-3}}\] Tesla |
| D. | \[\sqrt{5}\times {{10}^{-3}}\] Tesla |
| Answer» E. | |
| 5585. |
A small bar magnet has a magnetic moment 1.2 A-m2. The magnetic field at a distance 0.1 m on its axis will be : (m0 = 4p ´ 10?7 T-m/A) [BHU 2003] |
| A. | 1.2 ´ 10?4 T |
| B. | 2.4 ´ 10?4 T |
| C. | 2.4 ´ 104 T |
| D. | 1.2 ´ 104 T |
| Answer» C. 2.4 ´ 104 T | |
| 5586. |
Ratio of magnetic intensities for an axial point and a point on broad side-on position at equal distance d from the centre of magnet will be or The magnetic field at a distance d from a short bar magnet in longitudinal and transverse positions are in the ratio [CPMT 1978, 82; KCET 1998] |
| A. | 1 : 1 |
| B. | 2 : 3 |
| C. | 2 : 1 |
| D. | 3 : 2 |
| Answer» D. 3 : 2 | |
| 5587. |
The effective length of a magnet is 31.4 cm and its pole strength is 0.5 Am. The magnetic moment, if it is bent in the form of a semicircle will be [DPMT 2003] |
| A. | \[0.1\,\,A{{m}^{2}}\] |
| B. | \[0.01\,\,A{{m}^{2}}\] |
| C. | \[0.2\,\,A{{m}^{2}}\] |
| D. | \[1.2\,\,A{{m}^{2}}\] |
| Answer» B. \[0.01\,\,A{{m}^{2}}\] | |
| 5588. |
The magnetic potential at a point on the axial line of a bar magnet of dipole moment M is V. What is the magnetic potential due to a bar magnet of dipole moment \[\frac{M}{4}\] at the same point [MH CET 2004] |
| A. | \[4\,V\] |
| B. | \[2\,V\] |
| C. | \[\frac{V}{2}\] |
| D. | \[\frac{V}{4}\] |
| Answer» E. | |
| 5589. |
The magnetic moment of a magnet of length 10 cm and pole strength 4.0 Am will be [DPMT 2003] |
| A. | \[0.4\,\,A{{m}^{2}}\] |
| B. | \[1.6\,\,A{{m}^{2}}\] |
| C. | \[20\,\,A{{m}^{2}}\] |
| D. | \[8.0\,\,A{{m}^{2}}\] |
| Answer» B. \[1.6\,\,A{{m}^{2}}\] | |
| 5590. |
A magnet of magnetic moment \[2\,J\,{{T}^{-1}}\] is aligned in the direction of magnetic field of 0.1 T. What is the net work done to bring the magnet normal to the magnetic field [DCE 2004] |
| A. | 0.1 J |
| B. | 0.2 J |
| C. | 1 J |
| D. | 2 J |
| Answer» C. 1 J | |
| 5591. |
A bar magnet of length 3 cm has points A and B along its axis at distances of 24 cm and 48 cm on the opposite sides. Ratio of magnetic fields at these points will be [DPMT 2004] |
| A. | 8 |
| B. | \[1/2\,\,\sqrt{2}\] |
| C. | 3 |
| D. | 4 |
| Answer» B. \[1/2\,\,\sqrt{2}\] | |
| 5592. |
Magnetic dipole moment is a [AFMC 2004] |
| A. | Scalar quantity |
| B. | Vector quantity |
| C. | Constant quantity |
| D. | None of these |
| Answer» C. Constant quantity | |
| 5593. |
The torque on a bar magnet due to the earth's magnetic field is maximum when the axis of the magnet is [MP PMT 2004] |
| A. | Perpendicular to the field of the earth |
| B. | Parallel to the vertical component of the earth's field |
| C. | At an angle of 33o with respect to the N-S direction |
| D. | Along the North-South (N-S) direction |
| Answer» B. Parallel to the vertical component of the earth's field | |
| 5594. |
The work done in rotating a magnet of magnetic moment 2 A-m2 in a magnetic field of 5 ´ 10?3 T from the direction along the magnetic field to opposite direction to the magnetic field, is [MP PET 2003] |
| A. | Zero |
| B. | 2 ´ 10?2 J |
| C. | 10?2 J |
| D. | 10 J |
| Answer» C. 10?2 J | |
| 5595. |
If a magnet is hanged with its magnetic axis then it stops in [AFMC 2003] |
| A. | Magnetic meridian |
| B. | Geometric meridian |
| C. | Angle of dip |
| D. | None of these |
| Answer» B. Geometric meridian | |
| 5596. |
The magnetic lines of force inside a bar magnet [AIEEE 2003] |
| A. | Are from south-pole to north-pole of the magnet |
| B. | Are from north-pole to south-pole of the magnet |
| C. | Do not exist |
| D. | Depend upon the area of cross-section of the bar magnet |
| Answer» B. Are from north-pole to south-pole of the magnet | |
| 5597. |
The distance of two points on the axis of a magnet from its centre is 10 cm and 20 cm respectively. The ratio of magnetic intensity at these points is 12.5 : 1. The length of the magnet will be |
| A. | 5 cm |
| B. | 25 cm |
| C. | 10 cm |
| D. | 20 cm |
| Answer» D. 20 cm | |
| 5598. |
The ultimate individual unit of magnetism in any magnet is called [MP PET 2002; J & K CET 2004] |
| A. | North pole |
| B. | South pole |
| C. | Dipole |
| D. | Quadrupole |
| Answer» D. Quadrupole | |
| 5599. |
Two lines of force due to a bar magnet [MP PMT 2002] |
| A. | Intersect at the neutral point |
| B. | Intersect near the poles of the magnet |
| C. | Intersect on the equatorial axis of the magnet |
| D. | Do not intersect at all |
| Answer» E. | |
| 5600. |
A bar magnet of magnetic moment 3.0 A-m2 is placed in a uniform magnetic induction field of 2 ´ 10?5 T. If each pole of the magnet experiences a force of 6 ´ 10?4 N, the length of the magnet is [EAMCET (Med.) 2000] |
| A. | 0.5 m |
| B. | 0.3 m |
| C. | 0.2 m |
| D. | 0.1 m |
| Answer» E. | |