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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 251. |
Curies law can be written asA. `chipropto(T-T_(C))`B. `chipropto(1)/(T-T_(C))`C. `chipropto(1)/(T)`D. `chiproptoT` |
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Answer» Correct Answer - C |
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| 252. |
A superconductor exhibits perfectA. FerrimagnetismB. FerromagnetismC. ParamagnetismD. Diamagnetism |
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Answer» Correct Answer - D |
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| 253. |
The magnetic moment of a current (i) carrying circular coil of radius (r) and number of turns (n) varies asA. `1//r^2`B. `1//r `C. `r `D. `r^(2) ` |
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Answer» Correct Answer - D From the formula , the magnetic moment of a current carrying circular coil is given by `M=niA-nipir^2` where , r is the radius of circular coil. Therefore , magnetic moment is proportional to ` r^(2)`. |
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| 254. |
A particle of charge `q` and mass `m` moves in a circular orbit of radius `r` with angular speed `omega`. The ratio of the magnitude of its magnetic moment to that of its angular momentum depends onA. `(q)/(2m)`B. `(q omega r^(2))/(2)`C. `(q omega)/(2m r^(2))`D. `( q omega r^(2))/(2m) ` |
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Answer» Correct Answer - A The relation between magnetic moment `(mu_l)` and angular momentum (L) is ` mu_l=-(q)/(2m)L` `implies (mu_l)/L=(q)/(2m)` The negative sign indicates that the angular momentum of the electron is opposite in direction to the magnetic moment. |
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| 255. |
Both the poles of a magnet |
| Answer» Correct Answer - T | |
| 256. |
The line joining the two poles of a magnet is called asA. Magnetic equatorB. Magnetic inductionC. Magnetic potentialD. Magnetic axis |
| Answer» Correct Answer - D | |
| 257. |
The S.I unit of magnetic dipole moment isA. `Am^(2)`B. `A^(2)m`C. AmD. `A^(-1)m^(-1)` |
| Answer» Correct Answer - A | |
| 258. |
SI unit of magnetic pole strength isA. `Am^(2)`B. `A^(2)m`C. AmD. `A^(-1)m^(-1)` |
| Answer» Correct Answer - C | |
| 259. |
If a circular coil area A,number of turns n carries a current I then it is equivalent to a magnetic dipole.The magnetic moment of a coil is,A. 2nIAB. nIAC. nIA/2D. `n^(2)IA` |
| Answer» Correct Answer - B | |
| 260. |
In a hydrogen atom,an electron revolves with a frequency of `6.8xx10^(9)`MHz in an orbit of diameter 1.06 Å.The equivalent magnetic moment isA. `9.5xx10^(-22) Am^(2)`B. `7.5xx10^(-10 Am^(2)`C. `4.5xx10^(-24) Am^(2)`D. `9.5xx10^(-24) Am^(2)` |
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Answer» Correct Answer - D F=`6.8xx10^(9) MHZ,r=0.53 A^(@),M=?` M=IA `=qfpir^(2)`ltbrge`1.6xx10^(-19)xx6.8xx10^(9)xx10^(6)xx3.14xx(0.53xx10^(-10))^(2)` `=9.5xx10^(-24)Am^(2)` |
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| 261. |
A circular coil of radius 4 cm having 20 turns carries a current of 3A.It is a magnetic field of intensity 0.5 `Wb//m^(2)`.The magnetic dipole moment of the coil isA. `0.3 Am^(2)`B. `1.3 Am^(2)`C. `0.15 Am^(2)`D. `0.6 Am^(2)` |
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Answer» Correct Answer - A r=4cm,n=20,I=3A,B=0.5T,M=? M=nIAltbrge`nlpir^(2)`ltbrge`20xx3xx3.14xx16xx10^(-4)` `=0.3 Am^(2)` |
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| 262. |
Two short bar magnets of moment each `100 A-m^(2)`are placed as shown in figure at the corners of a square of side 10 cm.The magnetic induction at P is A. ZeroB. `2sqrt(2)xx10^(-2) T`C. `sqrt(2) xx10^(-2)T`D. `2xx10^(-2)T` |
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Answer» Correct Answer - C `B_(1)=B_(2)` `=(mu_(0))/(4pi)(M)/(d^(3))=10^(-7)x(10^(2))/(10^(-3))=10^(-2)T` `B=sqrt(B_(1)^(2)+B_(2)^(2)2B_(1)B_(2)cos90^(@))`ltbrge`sqrt(B_(1)^(2)+B_(2)^(2))=sqrt((10^(-2))^(2)+(10^(-2))^(-2))` `=10^(2)sqrt(2) T.` |
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| 263. |
The only property possessed by ferromagnetic substance isA. HysteresisB. SusceptibilityC. Directional propertyD. Attracting magnetic substances |
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Answer» Correct Answer - A |
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| 264. |
Iron shows its ferromagnetic property atA. Below `770^(@)`CB. Above `770^(@)`CC. All temperaturesD. Normal tempratures |
| Answer» Correct Answer - B | |
| 265. |
Write a note on earth's magnetic field ? |
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Answer» The strength of the earth magnetic field value being of the order of 10 T. The magnetic field is now thought to arise due to electrical currents produced by convective motion of metallic fluids (consisting mostly of molten iron and nickel) in the outer core of the earth. This is known as the dynamo effect. The magnetic field lines of the earth resemble that of a (hypothetical) magnetic dipole located at the centre of the earth. The axis of the dipole does not coincide with the axis of rotation of the earth but is presently titled by approximately 11º.3" with respect to the later. In this way of looking at it, the magnetic poles are located where the magnetic field lines due to the dipole enter or leave the earth. The location of the north magnetic pole is at a latitude of 79º.74” N and a longitude of 71.8” W, a place somewhere in north Canada. The magnetic south pole is at 79º.74” S, 108º.22” E in the Antarctica. The pole near the geographic north pole of the earth is called the north magnetic pole. Likewise, the pole near the geographic south pole is called the south magnetic pole. There is some confusion in the nomenclature of the poles. If one looks at the magnetic field lines of the earth , one sees that unlike in the case of a bar magnet, the field lines go into the earth at the north magnetic pole (Nm) and come out from the south magnetic pole (Sm). The convention arose because the magnetic north was the direction to which the north pole of a magnetic needle pointed; the north pole of a magnet was so named as it was the north seeking pole. Thus, in reality, the north magnetic pole behaves like the south pole of a bar magnet inside the earth and vice versa. |
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| 266. |
Match the following:(i) H. C. Oersted(a) Cyclotron(ii) William Gilbert(b) Magnetic Lorentz force(iii) Lawrence(c) Electromagnetism(iv) Lorentz(d)Earth powerful magnet |
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Answer» (i) → (c) (ii) → (d) (iii) → (a) (iv) → (b) |
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| 267. |
The direction of line of magnetic field of bar magnet isA. From south pole to north poleB. From north pole to south poleC. Across the bar magnetD. From south pole to north pole inside the magnet and from north pole to south pole outside the magnet |
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Answer» Correct Answer - D |
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| 268. |
The magnetic induction due to short magnetic dipole of moment `0.1" A m"^(2)` at equatorial point 1 cm away from centre of dipole is `(mu_(0)=4pi xx 10^(-7) Wb//A m)`A. 0.1TB. 0.01 TC. 0.001TD. 0.0001 T |
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Answer» Correct Answer - B `B=(mu_(0))/(4pi)(M)/(r^(3))=(4pixx10^(-7)xx0.1)/(4pixx(10^(-2))^(3))=0.01T` |
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| 269. |
Write the following steps in a sequence to locate the neutral points when south pole of a bar magnet is placed towards geographical north. (A) Draw the magnetic lines of force due to the bar magnet by using a magnetic compass (B) locate the north the south poles of a bar magnet by using a magnetic compass (C) placea bar magnet on the white paper such that the south pole of the bar magnet point towards geographic north (D) Note the points the magnetic field where the magnetic compass does not show any particular directionA. CBADB. ACBDC. CABDD. BCAD |
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Answer» Correct Answer - D (i) Locate the north the south poles of a bar magnet by using a magnetic compass (ii) Place a bar magnet on the white paper such that the south pole of the bar magnet faces geographic north. (iii) Draw the magnetic lines of force produced due to the bar magnet by using a magnetic compass. (iv) note the points in the magnetic field where the magnetic compass does not show any particular direction. |
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| 270. |
State three differences between the temporary and permanent magnets. |
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Answer» Temporary magnet 1. It is made up of soft iron. 2. The magnet which loses its magnetism as soon as magnetising force is removed away from it. 3. Because of its weak power, it is not used to make iron piece into magnet. Permanent magnets 1. It is made up of steel, cobalt and nickel. 2. The magnet, which does not lose its magnetic properties easily is called permanent magnet. 3. It can convert ordinary piece of iron into a temporary magnet. |
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| 271. |
In which direction does a suspended bar magnet come to rest? Give reason. |
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Answer» A magnet always rests in North and South direction, i.e. N-end always towards North of Earth and S-end towards South of Earth. |
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| 272. |
The mass of an iron rod is `80 gm` and its magnetic moment is `10 Am^(2)`. If the density of iron is `8gm//c.c`. Then the value of intensity of magnetisation will beA. `10^(6)A//m`B. `10^(4)A//m`C. `10^(2)A//m`D. `10 A//m` |
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Answer» Correct Answer - A `I=(M)/(V),V=(mass)/(density)` |
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| 273. |
The magnet field lines due to a bar magnet are correctly shown in |
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Answer» Correct Answer - D Magnetic field lines of a magnet form closed continuous loops and are directed from north to south outside a magnet and they run from south to north poel inside the magnet . |
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| 274. |
Curie temperature is the temperature above whichA. A paramagnetic material becomes ferromagneticB. A ferromagnetic material becomes paramagneticC. A paramagnetic material becomes diamagneticD. A ferromagnetic material becomes diamagnetic |
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Answer» Correct Answer - B |
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| 275. |
The torque acting on a current carrying loop placed in an external uniform magnetic field does not depend on the ________A. shape of the loopB. strength of current through itC. strength of the magnetic fieldD. area of the loop |
| Answer» Correct Answer - A | |
| 276. |
The resultant magnetic moment for the following arrangement is |
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Answer» Correct Answer - A The resultant magnetic field is zero |
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| 277. |
A current carrying wire can deflect a magnetic needle. What is its effect on another current carrying wire kept near it ? |
| Answer» A current carrying wire produce a magnetic field around it | |
| 278. |
Which of the following statements is false of a place closer to the north pole ?A. VgtHB. V is nearly equal to IC. H is nearly equal to ID. `V=sqrt(I^(2)-H^(2))` |
| Answer» Correct Answer - C | |
| 279. |
A magnet is kept fixed with its length parallel to the magnetic meridian. An identical magnet is parallel to this such that its center lies on perpendicular bisector of both. If the second magnet is free to move, it will haveA. translatory motion onlyB. rotaional motion onlyC. both translatory and rotational motionD. vibrational motion only |
| Answer» Correct Answer - C | |
| 280. |
The effect due to uniform magnetic field on a freely suspended magnetic needle is as followsA. Both torque and net force are presentB. torque is present but no net forceC. Both torque and net force are absentD. net force is present but not torque |
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Answer» Correct Answer - B The effect due to uniform magnetic field on a freely suspended magnetic needle is torque but no net force . |
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| 281. |
The effect due to uniform magnetic field on a freely suspended magnetic needle is as followsA. both torque and net force are presentB. torque is present but no net forceC. both torque and net force are absentD. net force is present but no torque |
| Answer» Correct Answer - B | |
| 282. |
A bar magnet of moment `bar(M)` is in a magnetic field of induction `bar(B)`. Then the couple isA. `bar(M)xxbar(B)`B. `bar(B)xxbar(M)`C. `bar(M).bar(B)`D. `bar(B).bar(M)` |
| Answer» Correct Answer - A | |
| 283. |
The magnetic potential at a point due to pole of strength m at a distance r isA. `V=(pi_(0))/(4pi) (m)/(r)`B. `V=(pi_(0))/(pir) (m)/(r^(2))`C. `V=(pi_(0))/(4pi)(m)/(r^(3))`D. `V=(pi_(0))/(4pi) (2m)/(r)` |
| Answer» Correct Answer - A | |
| 284. |
Magnetic moment of a bar magnet is equal to a moment of a couple which is required to keep itA. Parallel to a uniform magnetic field of unit inductionB. Perpendicular to a uniform magnetic field of unit inductionC. Parallel to a uniform magnetic field of any inductionD. Perpendicular to a unifrom field of any induction |
| Answer» Correct Answer - B | |
| 285. |
The magnetic potential at any point due to short magnetic dipole isA. `V=(pi_(0))/(4pi) (M)/(r)`B. `V=(pi_(0))/(4pi) (M)/(r^(2)`C. `V=pn(pi_(0))/(4pi) (M)/(r^(2)`D. V=0 |
| Answer» Correct Answer - C | |
| 286. |
The magnetic potential at a point along the axis of a short magnetic dipole isA. `V=(mui_(0))/(4pi) (M)/(r^(2))`B. `V=-(mu_(0))/(4pi) (M)/(r^(2)`C. `V=pm(mu_(0))/(4pi) (M)/(r^(2))`D. V=0 |
| Answer» Correct Answer - C | |
| 287. |
Two isolated point poles of strength 30 Am and 60 Am are placed a distance of 0.3 m.The force of repulsion isA. `2xx10^(-3) N`B. `3 xx10^(-2) N`C. `4xx10^(-3)N`D. `3xx10^(-4) N` |
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Answer» Correct Answer - A `F=(mu_(0))/(4pi)(m_(1)m_(2))/(r^(2))` `=(10^(-7)xx30xx60)/(9xx10^(-2))=2xx10^(-3)N` |
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| 288. |
Two isolated point poles of strength 30 A-m and 60 A-m are placed at a distance of 0.3 m.The force of repulsion between them is(A) 2 × 10-3 N(B) 2 × 10-4 N(C) 2 × 105 N(D) 2 × 10-5 N |
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Answer» Correct option is: (A) 2 × 10-3 N |
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| 289. |
A very long magnet of pole strength `4 Am` is placed vertically with its one pole on the table. The distance form the pole, the neutral point will be formed is `(B_(H)=4xx10^(-5)T)`A. `0.5m`B. `0.1m`C. `0.15m`D. `6.66m` |
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Answer» Correct Answer - B `B_(H)=(mu_(0))/(4pi)(m)/(d^(3))` |
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| 290. |
The null points are on the axial line of a "bar" Magnet when it is placed such that its south pole pointsA. SouthB. EastC. NorthD. West |
| Answer» Correct Answer - C | |
| 291. |
A very long magnet is held vertically with its south pole on a table. A single neutral point is located on the table to theA. East of the magnetB. North of the magnetC. West of the magnetD. South of the magnet |
| Answer» Correct Answer - B | |
| 292. |
When `S-`pole of the given "bar" magnet is placed on a table pointing geographical `N-`poleA. two null points ar located on the axial line at equidistant on either sidesB. two null points are located on the equitorial line at equidistant on either sidesC. two null points ar located on the equitorial line only on one side of the magnetD. two null points are located on the equitorial line only on one side of the magnet |
| Answer» Correct Answer - A | |
| 293. |
There is no. couple acting when two bar magnets are placed co-axially separated by a distance becauseA. there are no forces on the poles.B. the forces are parallel and their lines of aciton do not coincideC. the forces are perpendicular to each otherD. the forces act along the same line |
| Answer» Correct Answer - D | |
| 294. |
A magnetic field is produce and directed along `y-`axis. A magnet is placed along `y-`axis. The direction of torque on the magnet is |
| Answer» Correct Answer - D | |
| 295. |
The major contribution of magnetism in substance is due toA. orbital motion of electronsB. spin motion of electronsC. equally due to orbital and spin motions of electronsD. hidden magnets |
| Answer» Correct Answer - B | |
| 296. |
The relative permeability of silicon is `0.99837` and that of palladium is `1.00692`, choose the correct options of the followingA. silicon is paramagnetic and palladium is ferromagneticB. silicon is ferromagnetic and palladium is paramagneticC. silicon is diamagnetic and palladium is paramagneticD. Both are paramagnetic |
| Answer» Correct Answer - C | |
| 297. |
Which of the following is ferromagneticA. QuartzB. NickelC. BismuthD. Aluminium |
| Answer» Correct Answer - B | |
| 298. |
Which of the following is a paramagnetic substance?A. AirB. WaterC. OxygenD. Copper |
| Answer» Correct Answer - C | |
| 299. |
A rod of a paramagnetic material such as aluminium is suspended in a uniform storng magnetic field.How will it align it self in the field?A. B. C. D. |
| Answer» Correct Answer - C | |
| 300. |
If a paramagnetic substance is placed in a non uniform magnetic field then it will move fromA. Weak field to strongB. Strong to weak fieldC. Remains stbleD. None of these |
| Answer» Correct Answer - A | |