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.
| 5601. |
There is no couple acting when two bar magnets are placed coaxially separated by a distance because [EAMCET (Engg.) 2000] |
| A. | There are no forces on the poles |
| B. | The forces are parallel and their lines of action do not coincide |
| C. | The forces are perpendicular to each other |
| D. | The forces act along the same line |
| Answer» E. | |
| 5602. |
A bar magnet is held perpendicular to a uniform magnetic field. If the couple acting on the magnet is to be halved by rotating it, then the angle by which it is to be rotated is [CBSE PMT 2000] |
| A. | 30o |
| B. | 45o |
| C. | 60o |
| D. | 90o |
| Answer» D. 90o | |
| 5603. |
A magnet of magnetic moment \[50\,\hat{i}\,A\text{-}{{m}^{2}}\] is placed along the x-axis in a magnetic field \[\overrightarrow{B}=(0.5\,\hat{i}+3.0\hat{j})\,T.\] The torque acting on the magnet is [MP PMT 2000] |
| A. | 175 \[\hat{k}\,\,N\text{-}m\] |
| B. | 150 \[\hat{k}\,\,N\text{-}m\] |
| C. | 75 \[\hat{k}\,\,N\text{-}m\] |
| D. | \[25\sqrt{37}\,\hat{k}\,\,N\text{-}m\] |
| Answer» C. 75 \[\hat{k}\,\,N\text{-}m\] | |
| 5604. |
Two similar bar magnets P and Q, each of magnetic moment M, are taken, If P is cut along its axial line and Q is cut along its equatorial line, all the four pieces obtained have [EAMCET (Engg.) 2000] |
| A. | Equal pole strength |
| B. | Magnetic moment \[\frac{M}{4}\] |
| C. | Magnetic moment \[\frac{M}{2}\] |
| D. | Magnetic moment M |
| Answer» D. Magnetic moment M | |
| 5605. |
A bar magnet of magnetic moment 200 A-m2 is suspended in a magnetic field of intensity 0.25 N/A-m. The couple required to deflect it through 30o is [AFMC 1999; Pb. PET 2000] |
| A. | 50 N-m |
| B. | 25 N-m |
| C. | 20 N-m |
| D. | 15 N-m |
| Answer» C. 20 N-m | |
| 5606. |
If a magnet of pole strength m is divided into four parts such that the length and width of each part is half that of initial one, then the pole strength of each part will be |
| A. | \[m/4\] |
| B. | \[m/2\] |
| C. | \[m/8\] |
| D. | \[4m\] |
| Answer» C. \[m/8\] | |
| 5607. |
The intensity of magnetic field is H and moment of magnet is M. The maximum potential energy is [Pb. PMT 1999; MH CET (Med.) 1999] |
| A. | MH |
| B. | 2 MH |
| C. | 3 MH |
| D. | 4 MH |
| Answer» B. 2 MH | |
| 5608. |
If a magnet of length 10 cm and pole strength 40 A-m is placed at an angle of 45o in an uniform induction field of intensity 2 ´ 10?4 T, the couple acting on it is [Pb. PMT 1999; MH CET (Med.) 1999] |
| A. | 0.5656 ´ 10?4 N-m |
| B. | 0.5656 ´ 10?3 N-m |
| C. | 0.656 ´ 10?4 N-m |
| D. | 0.656 ´ 10?5 N-m |
| Answer» C. 0.656 ´ 10?4 N-m | |
| 5609. |
Two like magnetic poles of strength 10 and 40 SI units are separated by a distance 30 cm. The intensity of magnetic field is zero on the line joining them [JIPMER 1999] |
| A. | At a point 10 cm from the stronger pole |
| B. | At a point 20 cm from the stronger pole |
| C. | At the mid-point |
| D. | At infinity |
| Answer» C. At the mid-point | |
| 5610. |
Two magnets, each of magnetic moment ?M? are placed so as to form a cross at right angles to each other. The magnetic moment of the system will be [AFMC 1999; Pb PET 2001] |
| A. | 2 M |
| B. | \[\sqrt{2}\,M\] |
| C. | 0.5 M |
| D. | M |
| Answer» C. 0.5 M | |
| 5611. |
Weber/m2 is equal to [CPMT 1985; AFMC 1997] |
| A. | Volt |
| B. | Henry |
| C. | Tesla |
| D. | All of these |
| Answer» D. All of these | |
| 5612. |
A magnet when placed perpendicular to a uniform field of strength \[{{10}^{-4}}Wb/{{m}^{2}}\] experiences a maximum couple of moment\[4\times {{10}^{-5}}N/m.\]. What is its magnetic moment [Bihar MEE 1995] |
| A. | \[0.4A\times {{m}^{2}}\] |
| B. | \[0.2A\times {{m}^{2}}\] |
| C. | \[0.16A\times {{m}^{2}}\] |
| D. | \[0.04A\times {{m}^{2}}\] (e) \[0.06A\times {{m}^{2}}\] |
| Answer» B. \[0.2A\times {{m}^{2}}\] | |
| 5613. |
The magnet can be completely demagnetized by [KCET 1994] |
| A. | Breaking the magnet into small pieces |
| B. | Heating it slightly |
| C. | Droping it into ice cold water |
| D. | A reverse field of appropriate strength |
| Answer» E. | |
| 5614. |
If a piece of metal was thought to be magnet, which one of the following observations would offer conclusive evidence [KCET 1994] |
| A. | It attracts a known magnet |
| B. | It repels a known magnet |
| C. | Neither (a) nor (b) |
| D. | It attracts a steel screw driver |
| Answer» C. Neither (a) nor (b) | |
| 5615. |
For protecting a sensitive equipment from the external magnetic field, it should be [KCET 1993; CBSE PMT 1998] |
| A. | Placed inside an aluminium cane |
| B. | Placed inside an iron cane |
| C. | Wrapped with insulation around it when passing current through it |
| D. | Surrounded with fine copper sheet |
| Answer» C. Wrapped with insulation around it when passing current through it | |
| 5616. |
Points A and B are situated along the extended axis of 2 cm long bar magnet at a distance x and 2x cm respectively. From the pole nearer to the points, the ratio of the magnetic field at A and B will be [EAMCET 1984; CPMT 1986] |
| A. | 4 : 1 exactly |
| B. | 4 : 1 approx. |
| C. | 8 : 1 exactly |
| D. | 8 : 1 approx. |
| Answer» E. | |
| 5617. |
A bar magnet of magnetic moment \[\overrightarrow{M}\] is placed in a magnetic field of induction \[\overrightarrow{B}\]. The torque exerted on it is [EAMCET (Engg.) 1995; CBSE PMT 1999; BHU 2003; CPMT 2004; MP PMT 2001, 05] |
| A. | \[\overrightarrow{M}.\overrightarrow{B\,}\] |
| B. | ? \[\overrightarrow{M}.\overrightarrow{B\,}\] |
| C. | \[\overrightarrow{M}\times \overrightarrow{B\,}\] |
| D. | \[\overrightarrow{B\,}\times \overrightarrow{M}\] |
| Answer» D. \[\overrightarrow{B\,}\times \overrightarrow{M}\] | |
| 5618. |
A straight wire carrying current i is turned into a circular loop. If the magnitude of magnetic moment associated with it in M.K.S. unit is M, the length of wire will be [MP PET 1999] |
| A. | \[4\pi iM\] |
| B. | \[\sqrt{\frac{4\pi M}{i}}\] |
| C. | \[\sqrt{\frac{4\pi i}{M}}\] |
| D. | \[\frac{M\pi }{4i}\] |
| Answer» C. \[\sqrt{\frac{4\pi i}{M}}\] | |
| 5619. |
The incorrect statement regarding the lines of force of the magnetic field B is [MP PET 1999] |
| A. | Magnetic intensity is a measure of lines of force passing through unit area held normal to it |
| B. | Magnetic lines of force form a close curve |
| C. | Inside a magnet, its magnetic lines of force move from north pole of a magnet towards its south pole |
| D. | Due to a magnet magnetic lines of force never cut each other |
| Answer» D. Due to a magnet magnetic lines of force never cut each other | |
| 5620. |
The magnetic field to a small magnetic dipole of magnetic moment M, at distance r from the centre on the equatorial line is given by (in M.K.S. system) [MP PMT/PET 1998] |
| A. | \[\frac{{{\mu }_{0}}}{4\pi }\times \frac{M}{{{r}^{2}}}\] |
| B. | \[\frac{{{\mu }_{0}}}{4\pi }\times \frac{M}{{{r}^{3}}}\] |
| C. | \[\frac{{{\mu }_{0}}}{4\pi }\times \frac{2M}{{{r}^{2}}}\] |
| D. | \[\frac{{{\mu }_{0}}}{4\pi }\times \frac{2M}{{{r}^{3}}}\] |
| Answer» C. \[\frac{{{\mu }_{0}}}{4\pi }\times \frac{2M}{{{r}^{2}}}\] | |
| 5621. |
The S.I. unit of magnetic permeability is [MP PET 1997] |
| A. | \[A{{m}^{-1}}\] |
| B. | \[Am\] |
| C. | \[Henry\,{{m}^{-1}}\] |
| D. | No unit, it is a dimensionless number |
| Answer» D. No unit, it is a dimensionless number | |
| 5622. |
A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.16 Tesla experiences a torque of magnitude 0.032 Joule. The magnetic moment of the bar magnet will be [MP PMT 1997; UPSEAT 2004] |
| A. | 0.23 Joule/Tesla |
| B. | 0.40 Joule/Tesla |
| C. | 0.80Joule/Tesla |
| D. | Zero |
| Answer» C. 0.80Joule/Tesla | |
| 5623. |
Two equal bar magnets are kept as shown in the figure. The direction of resultant magnetic field, indicated by arrow head at the point P is (approximately) |
| A. | |
| B. | |
| C. | |
| D. | |
| Answer» C. | |
| 5624. |
A permanent magnet [MP PET 1996] |
| A. | Attracts all substances |
| B. | Attracts only magnetic substances |
| C. | Attracts magnetic substances and repels all non-magnetic substances |
| D. | Attracts non-magnetic substances and repels magnetic substances |
| Answer» C. Attracts magnetic substances and repels all non-magnetic substances | |
| 5625. |
The dipole moment of a short bar magnet is 1.25 A-m2. The magnetic field on its axis at a distance of 0.5metre from the centre of the magnet is |
| A. | \[1.0\times {{10}^{-4}}Newton/amp-meter\] |
| B. | \[4\times {{10}^{-2}}Newton/amp-metre\] |
| C. | \[2\times {{10}^{-6}}Newton/amp-metre\] |
| D. | \[6.64\times {{10}^{-8}}Newton/amp-metre\] |
| Answer» D. \[6.64\times {{10}^{-8}}Newton/amp-metre\] | |
| 5626. |
A magnet of magnetic moment M and pole strength m is divided in two equal parts, then magnetic moment of each part will be [MP Board 1985; MP PET 1984, 2000; NCERT 1974; AFMC 1996; MP PMT 2002; MH CET (Med.) 2001; CPMT 1983, 84; KCET 1994, 2001] |
| A. | \[M\] |
| B. | \[M/2\] |
| C. | \[M/4\] |
| D. | \[2M\] |
| Answer» C. \[M/4\] | |
| 5627. |
Magnetic lines of force due to a bar magnet do not intersect because [MP PMT 1995] |
| A. | A point always has a single net magnetic field |
| B. | The lines have similar charges and so repel each other |
| C. | The lines always diverge from a single point |
| D. | The lines need magnetic lenses to be made to intersect |
| Answer» B. The lines have similar charges and so repel each other | |
| 5628. |
A bar magnet of magnetic moment 104J/T is free to rotate in a horizontal plane. The work done in rotating the magnet slowly from a direction parallel to a horizontal magnetic field of 4×10?5 T to a direction 60° from the field will be [MP PET 1995] |
| A. | 0.2 J |
| B. | 2.0 J |
| C. | 4.18 J |
| D. | 2 × 102 J |
| Answer» B. 2.0 J | |
| 5629. |
Force between two identical bar magnets whose centres are r metre apart is 4.8 N, when their axes are in the same line. If separation is increased to 2r, the force between them is reduced to [AIIMS 1995] |
| A. | 2.4N |
| B. | 1.2N |
| C. | 0.6N |
| D. | 0.3N |
| Answer» E. | |
| 5630. |
The work done in turning a magnet of magnetic moment 'M' by an angle of 90° from the meridian is 'n' times the corresponding work done to turn it through an angle of 60°, where 'n' is given by [CBSE PMT 1995; MP PET 2003] |
| A. | 1/2 |
| B. | 2 |
| C. | 1/4 |
| D. | 1 |
| Answer» C. 1/4 | |
| 5631. |
The direction of line of magnetic field of bar magnet is [AFMC 1995] |
| A. | From south pole to north pole |
| B. | From north pole to south pole |
| C. | Across the bar magnet |
| D. | From south pole to north pole inside the magnet and from north pole to south pole outside the magnet |
| Answer» E. | |
| 5632. |
A magnet of magnetic moment M is rotated through 360° in a magnetic field H, the work done will be [KCET 1998; MP PMT 1994; Roorkee 2000] |
| A. | MH |
| B. | 2MH |
| C. | \[2\pi MH\] |
| D. | Zero |
| Answer» E. | |
| 5633. |
Rate of change of torque \[\tau \] with deflection\[\theta \]is maximum for a magnet suspended freely in a uniform magnetic field of induction B, when [MP PET 1994] |
| A. | \[\theta =0{}^\circ \] |
| B. | \[\theta =45{}^\circ \] |
| C. | \[\theta =60{}^\circ \] |
| D. | \[\theta =90{}^\circ \] |
| Answer» B. \[\theta =45{}^\circ \] | |
| 5634. |
Magnetic lines of force [MP PET 1994] |
| A. | Always intersect |
| B. | Are always closed |
| C. | Tend to crowd far away from the poles of magnet |
| D. | Do not pass through vacuum |
| Answer» C. Tend to crowd far away from the poles of magnet | |
| 5635. |
The small magnets each of magnetic moment 10 A-m2 are placed end-on position 0.1m apart from their centres. The force acting between them is [MNR 1994] |
| A. | \[0.6\times {{10}^{7}}N\] |
| B. | \[0.06\times {{10}^{7}}N\] |
| C. | \[0.6N\] |
| D. | \[0.06N\] |
| Answer» D. \[0.06N\] | |
| 5636. |
If a hole is made at the centre of a bar magnet, then its magnetic moment will |
| A. | Increase |
| B. | Decrease |
| C. | Not change |
| D. | None of these |
| Answer» D. None of these | |
| 5637. |
A magnet is placed in iron powder and then taken out, then maximum iron powder is at |
| A. | Some away from north pole |
| B. | Some away from south pole |
| C. | The middle of the magnet |
| D. | The end of the magnet |
| Answer» E. | |
| 5638. |
Force between two unit pole strength placed at a distance of one metre is [CPMT 1987] |
| A. | 1 N |
| B. | \[\frac{{{10}^{-7}}}{4\pi }N\] |
| C. | \[{{10}^{-7\,}}\,N\] |
| D. | \[4\pi \times {{10}^{-7}}N\] |
| Answer» D. \[4\pi \times {{10}^{-7}}N\] | |
| 5639. |
A small bar magnet of moment M is placed in a uniform field H. If magnet makes an angle of 30° with field, the torque acting on the magnet is [CPMT 1989] |
| A. | MH |
| B. | \[\frac{MH}{2}\] |
| C. | \[\frac{MH}{3}\] |
| D. | \[\frac{MH}{4}\] |
| Answer» C. \[\frac{MH}{3}\] | |
| 5640. |
What happens to the force between magnetic poles when their pole strength and the distance between them are both doubled [CPMT 1978, 80, 84, 85; MP PET 2005] |
| A. | Force increases to two times the previous value |
| B. | No change |
| C. | Force decreases to half the previous value |
| D. | Force increases to four times the previous value |
| Answer» C. Force decreases to half the previous value | |
| 5641. |
Magnetic induction is a [AFMC 1986] |
| A. | Scalar quantity |
| B. | Vector quantity |
| C. | Both (a) and (b) |
| D. | None of the above |
| Answer» C. Both (a) and (b) | |
| 5642. |
Two identical thin bar magnets each of length l and pole strength m are placed at right angle to each other with north pole of one touching south pole of the other. Magnetic moment of the system is [MNR 1981; MP PET 2002] |
| A. | ml |
| B. | 2ml |
| C. | \[\sqrt{2}ml\] |
| D. | \[\frac{1}{2}ml\] |
| Answer» D. \[\frac{1}{2}ml\] | |
| 5643. |
A magnetic needle lying parallel to a magnetic field requires W units of work to turn it through 60°. The torque required to maintain the needle in this position will be [KCET 1994; MNR 1991; MP PET 1996; [AIEEE 2003; UPSEAT 2000; BHU 2004; Pb PET 2004] |
| A. | \[\sqrt{3}\,W\] |
| B. | W |
| C. | \[\frac{\sqrt{3}}{2}W\] |
| D. | 2W |
| Answer» B. W | |
| 5644. |
A long magnetic needle of length 2L, magnetic moment M and pole strength m units is broken into two pieces at the middle. The magnetic moment and pole strength of each piece will be [NCERT 1983; DPMT 1987] |
| A. | \[\frac{M}{2},\frac{m}{2}\] |
| B. | \[M,\frac{m}{2}\] |
| C. | \[\frac{M}{2},m\] |
| D. | \[M,m\] |
| Answer» D. \[M,m\] | |
| 5645. |
The magnetic induction in air at a distance d from an isolated point pole of strength m unit will be [MNR 1987; CPMT 1991; MP PET 1995; AMU 1999; J & K CET 2005] |
| A. | \[\frac{m}{d}\] |
| B. | \[\frac{m}{{{d}^{2}}}\] |
| C. | \[md\] |
| D. | \[m{{d}^{2}}\] |
| Answer» C. \[md\] | |
| 5646. |
A magnetic needle is kept in a non-uniform magnetic field. It experiences [MP PMT 1987; IIT 1982; Kerala PET 2002; AMU 1999; AIEEE 2005] |
| A. | A force and a torque |
| B. | A force but not a torque |
| C. | A torque but not a force |
| D. | Neither a torque nor a force |
| Answer» B. A force but not a torque | |
| 5647. |
If the magnetic flux is expressed in weber, then magnetic induction can be expressed in [CPMT 1974, 77, 83, 86, 87; MP PET 1989] |
| A. | Weber/m2 |
| B. | Weber/m |
| C. | Weber-m |
| D. | Weber-m2 |
| Answer» B. Weber/m | |
| 5648. |
Magnetic intensity for an axial point due to a short bar magnet of magnetic moment M is given by [MP PET 1984; CPMT 1974; Pb. PMT 1999] |
| A. | \[\frac{{{\mu }_{0}}}{4\pi }\times \frac{M}{{{d}^{3}}}\] |
| B. | \[\frac{{{\mu }_{0}}}{4\pi }\times \frac{M}{{{d}^{2}}}\] |
| C. | \[\frac{{{\mu }_{0}}}{2\pi }\times \frac{M}{{{d}^{3}}}\] |
| D. | \[\frac{{{\mu }_{0}}}{2\pi }\times \frac{M}{{{d}^{2}}}\] |
| Answer» D. \[\frac{{{\mu }_{0}}}{2\pi }\times \frac{M}{{{d}^{2}}}\] | |
| 5649. |
Magnetic field intensity is defined as [MP PET 1993] |
| A. | Magnetic moment per unit volume |
| B. | Magnetic induction force acting on a unit magnetic pole |
| C. | Number of lines of force crossing per unit area |
| D. | Number of lines of force crossing per unit volume |
| Answer» C. Number of lines of force crossing per unit area | |
| 5650. |
A bar magnet of length 10 cm and having the pole strength equal to 10?3 weber is kept in a magnetic field having magnetic induction equal to \[4\pi \times {{10}^{-3}}\]Tesla. It makes an angle of 30o with the direction of magnetic induction. The value of the torque acting on the magnet is [MP PMT 1993] |
| A. | \[2\pi \times {{10}^{-7}}N\times m\] |
| B. | \[2\pi \times {{10}^{-5}}N\times m\] |
| C. | \[0.5N\times m\] |
| D. | \[0.5\times {{10}^{2}}N\times m\] (\[{{\mu }_{0}}=4\pi \times {{10}^{-7}}weber/amp\times m\]) |
| Answer» B. \[2\pi \times {{10}^{-5}}N\times m\] | |