InterviewSolution
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InterviewSolution
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. |
Which of the following is most suitable for the core of electromagnets?A. Soft ironB. SteelC. Copper-nickel alloyD. Air |
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Answer» Correct Answer - A Soft iron is highly ferromagnetic. |
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| 252. |
Two magnets have the same length and the same pole strenght . But one of the magnets have a small hole at its centre. ThenA. Both have equal magnetic momentB. One with hole has smaller magnetic momentC. One with hole has larger magnetic momentD. One with hole loses magnetism through the hole |
| Answer» Correct Answer - B | |
| 253. |
Demagnetization of magnets can be done byA. Rough handlingB. HeatingC. Magnetising in the opposite directionD. All of the above |
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Answer» Correct Answer - D Theory based |
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| 254. |
A magnetic needle lying parallel to a magnetic field requires W units of work to turn through `60^(@)` . The external torque required to maintain the magnetic needle in this position isA. WB. 2 WC. `(sqrt3)/(2) W`D. `sqrt3` W |
| Answer» Correct Answer - D | |
| 255. |
Torques `tau_(1)` and `tau_(2)` are required for a magnetic needle to remain perpendicular to the magnetic fields at two different places. The magnetic field at those places are B1 and B2 respectively, then `(B_(1))/(B_(2))` is |
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Answer» Correct Answer - B Torque, `tau=MB sintheta ` `tau_(1)=MB_(1) sin90^(@)=MB_(1)` `tau_(2)=MB_(2) sin90^(@)=MB_(2) or (MB_(1))/(MB_(2))=(tau_(1))/(tau_(2))` `(B_(1))/(B_(2))=(tau_(1))/(tau_(2))` n |
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| 256. |
A curve between magnetic moment and temperature of magnet isA. B. C. D. |
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Answer» Correct Answer - C Magnetism of a magnet falls with rise temperature and becomes partically zero above curie temperature. |
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| 257. |
A curve between magnetic moment and temperature of magnet is |
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Answer» Correct Answer - C Magnetism of a magnet falls with rise of temperature an becomes practically zero above Curie temperature. |
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| 258. |
Magnetic lines of force due to a bar magnet do not intersect becauseA. a point is always has a single net magnetic fieldB. the line is always diverge from a single pointC. the is always diverge froma single pointD. none of these |
| Answer» Magnetic lines of force due to a bar magnet do not intersect because if they intersect then it means, there are two direction of magnetic field intensity which is impossible. | |
| 259. |
Two solenoids acting as short bar magnets P and Q are arranged such that their centres are on the X-axis and are separated by a large distance. The magnetic axes of P and Q are along X and Y-axes, respectively. At a point R, midway between their centres, if B is the magnitude of induction due to Q , then the magnitude of total induction at R due to the magnitude isA. 3BB. `sqrtB`C. `(sqrt5)/(2)B`D. B |
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Answer» Since for magnet P, axis lies alonX-axis and for magnet Q, axis is along Y-axis. The point R is along axial line w.r.t. magnet P, and is along equalorital line w.r.t. magnet Q. Magnet field due to magnet Q `B_(Q)=(mu_(0))/(4pi) (M)/(x^(3))=B "[" "R Rightarrow equatorial point" "]"` magnetic field due to magnet P `B_(P)=(mu_(0))/(4pi) (2M)/(x^(3))=B "[" "R=axial point" "]"` As at a point R magnetic field due to P and Q magnet are perpendicular to each other, , `B_(R) Rightarrow` Net magnetic field due to magnet P and is given as Q. `B_(R) Rightarrow sqrt(B_(p)^(2)+B_(Q)^(2))=sqrt(B^(2)+(2B)^(2))=sqrt5B` |
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| 260. |
If `theta_1` and `theta_2` be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip `theta` is given byA. `tan^(2) theta=tan^(2) theta_(1)+tan^(2) theta_(2)`B. `cot^(2) theta=cot^(2) theta_(1)-cot^(2) theta_(2)`C. `tan^(2) theta=tan^(2) theta_(1)-tan^(2) theta_(2)`D. `cot^(2) theta=cot^(2) theta_(1)+cot^(2) theta_(2)` |
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Answer» Correct Answer - D `tantheta_(1)=(tantheta)/(cos alpha)` `implies tan theta_(2)=(tantheta)/(cos(90-alpha))=(tantheta)/(sin alpha)` `implies sin^(2) alpha+cos^(2) alpha=1` `implies cot^(2) theta_(2)+cot^(2)theta_(1)=cot^(2) theta` |
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| 261. |
A bar magnet of magnetic dipole moment `10 Am^(2)` is in stable equilibrium . If it is rotated through `30^(@)` , find its potential energy in new position [Given , B = 0.2 T] |
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Answer» `M = 10 A m^(2)` B = 0.2 T U = `- MB cos theta` = `-10 xx 0.2 xx (sqrt3)/(2)` `= - sqrt3 J` |
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| 262. |
A bar magnet of magnetic dipole moment 8 `Am^(2)` has poles separated by `0.4` m . Find the pole strength of bar magnet . |
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Answer» `M = q_(m) xx L` `B = q_(m) xx 0.4` `q_(m) = (8)/(0.4) = 20` Am |
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| 263. |
Let `r` be the distance of a point on the axis of a magnetic dipole from its centre. The magnetic field at such a point is proportional toA. 16AB. 8AC. 4AD. 2A |
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Answer» Correct Answer - B The coercivity of bar magnet `4xx10^(3)A-m^(-1)` Length of solenoid=12cm, Number of turns=60 The coercivity of 12cm length of solenoid `" " 4xx10^(3)xx12xx10^(-2)=480` Now, current through each turn to demagnetise =`(480)/(60)=8A` |
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| 264. |
The variation of magnetic susceptibility `(chi)` with temperature for dimagnetic substance is represented byA. B. C. D. |
| Answer» Correct Answer - D | |
| 265. |
When a ferromagnetic material is heated above its Curie temperature , the materialA. Becomes permanently magnetizedB. Becomes diamagneticC. Becomes paramagneticD. Remains ferromagnetic |
| Answer» Correct Answer - C | |
| 266. |
The variation of magnetic susceptibility `(chi)` with temperature for a diamagnetic substance is best represented by |
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Answer» Correct Answer - B For a diamagnetic substance `chi` is small, negative and independent of temperature. |
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| 267. |
Magnetic susceptibility of diamagnetic substances depends upon the absolute temperature T asA. `T^(1)`B. `T^(-1)`C. `T^(-2)`D. `T^(0)` |
| Answer» Correct Answer - D | |
| 268. |
The variation of magnetic susceptibility `(chi)` with temperature for a diamagnetic substance is best represented byA. B. C. D. |
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Answer» Correct Answer - B For a diamagetic substance , x is small, negative and independent of temperature. |
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| 269. |
A certain amount of current when flowing in a properly set tangent galvanoment, produces a deflection of `45^(@)`. If the current be reduced by a factor of `sqrt(3)`, the deflection wouldA. Decrease by `30^(@)`B. Decrease by `15^(@)`C. Increase by `15^(@)`D. Increase by `30^(@)` |
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Answer» Correct Answer - B In tangent galvanometer, `I prop tan theta` :. `I_(1)/I_(2)=(tantheta_(1))/(tantheta_(2)) impliesI_(1)/(I_(1)//sqrt(3))=(tan 45^(@))/(tantheta_(2))` `implies sqrt(3)tantheta_(2)=1 implies tantheta_(2)= 1/sqrt(3) implies theta_(2)=30^(@)` So deflection will decrease by `45^(@)-30^(@)=15^(@)` |
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| 270. |
When `2` amperes current is passed through a tangent galvanometer, it gives a deflection of `30^(@)`. For `60^(@)` deflection, the current must beA. `1 amp`B. `2sqrt(3) amp`C. `4 amp`D. `6 amp` |
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Answer» Correct Answer - D `i prop tan varphiimplies i_(1)/i_(2)=(tan varphi_(1))/(tan varphi_(2))` `implies 2/i_(2)=(tan 30)/(tan 60) implies i_(2)=6 amp` |
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| 271. |
In a tangent galvanometer a current of `0.1 A` produces a deflection of `30^(@)`. The current required to produce a deflection of `60^(@)` isA. `0.2A`B. `0.3A`C. `0.4A`D. `0.5A` |
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Answer» Correct Answer - B `i prop tan varphiimpliesi_(1)/i_(2)=(tan varphi_(1))/(tan varphi_(2))` `implies0.1/i_(2)=(tan 30^(@))/(tan 60^(@))=1/3impliesi_(2)=0.3A` |
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| 272. |
A paramagnetic liquid is taken in a U-tube and arranged so that one of its limbs is kept between pole pieces of the magnet. The liquid level in the limbA. goes downB. rise upC. remains sameD. first goes down and then rise |
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Answer» Correct Answer - B The liquid rises up in the part of the tube which is between the poles. |
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| 273. |
The bob of a simple pendulim is replaced by a magnet. The oscillations are set along the length of the magnet. A copper coil is added so that one pole of the magnet passes in and out of coil. The coil is sort-circuited. Then which one of the following happens?A. Period decreasesB. Period does not changeC. Oscillations are dampedD. Amplitide increases |
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Answer» Correct Answer - C It is due to the magnetic field produced by coil. |
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| 274. |
Current senstivity of moving coil galvanometer is `5 "div"//mA` and its voltage senstivity (angular deflection per unit voltage applied) is `20 "div"//V`. The resistance of the galvanometer isA. `40 Omega`B. `25 Omega`C. `250 Omega`D. `500 Omega` |
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Answer» Correct Answer - C Current sensitivity `theta/i=5/10^(-3)=5000"div"/A …(i)` Velocity sensitivity `theta/V=20` From (i)//(ii), we get `(theta//i)/(theta//V)=5000/10=250` `implies V/i=R=250 Omega` |
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