NEET-2022
Question 1. The shape of the magnetic field lines due to an infinite long, straight current carrying conductor is
(a) a plane
(b) a straight line
(c) circular
(d) elliptical
Answer (c)
Question 2. Two very long, straight, parallel conductors `A` and `B` carry current of `5 A` and `10 A` respectively and are at a distance of `10 cm` from each other. The direction of current in two conductors is same. The force acting per unit length between two conductors is :
`(\mu_0=4\pi\times10^-7)` SI unit
(a) `1\times10^-4Nm^-1` and is repulsive
(b) `2\times10^-4Nm^-1` and is attractive
(c) `2\times10^-4Nm^-1` and is repulsive
(d) `1\times10^-4Nm^-1` and is attractive
Answer (d)
Question 3. The magnetic field on the axis of a circular loop of radius `100 cm` carrying current `I=\sqrt{2}A`, at point `1 m` away from the centre of the loop is given by :
(a) `6.28\times10^-4T`
(b) `3.14\times10^-7T`
(c) `6.28\times10^-7T`
(d) `3.14\times10^-4T`
Answer (b)
Question 4. A long solenoid of radius `1 mm` has `100` turns per mm. If `1 A` current flows in the solenoid, the magnetic field strength at the centre of the solenoid is
(a) `6.28\times10^-2T`
(b) `12.56\times10^-2T`
(c) `12.56\times10^-4T`
(d) `6.28\times10^-4T`
Answer (b)
Question 5. Given below are two statements:
Statement I : Biot-Savart's law gives us the expression for the magnetic field strength of an infinitesimal current element (Idl) of a current carrying conductor only.
Statement II : Biot-Savart's law is analogous to Coulomb's inverse square law of charge q, with the former being related to the field produced by a scalar source, Idl while the latter being produced by a vector source, q.
In light of above statements choose the most appropriate answer from the options given below.
(a) Both Statement I and Statement II are correct
(b) Both Statement I and Statement II are incorrect
(c) Statement I is correct and Statement II is incorrect
(d) Statement I is incorrect and Statement II is correct
Answer (c)
Question 6. A square loop of side `1 m` and resistance `1\Omega` is placed in a magnetic field of `0.5 T`. If the plane of loop is perpendicular to the direction of magnetic field, the magnetic flux through the loop is
(a) `2` weber
(b) `0.5` weber
(c) `1` weber
(d) Zero weber
Answer (b)
Question 7. From Ampere's circuital law for a long straight wire of circular cross-section carrying a steady current, the variation of magnetic field in the inside and outside region of the wire is
(a) Uniform and remains constant for both the regions.
(b) A linearly increasing function of distance upto the boundary of the wire and then linearly decreasing for the outside region.
(c) A linearly increasing function of distance r upto the boundary of the wire and then decreasing one with `1/r` dependence for the outside region.
(c) A linearly decreasing function of distance upto the boundary of the wire and then a linearly increasing one of the outside region.
Answer (c)
Question 8. An infinitely long straight conductor carries a current of `5A` as shown. An electron is moving with a speed of `105 m/s` parallel to the conductor. The perpendicular distance between the electron and the conductor is `20cm` at an instant. Calculate the magnitude of the force experienced by the electron at that instant.
(a) `8\times10^-20N`
(b) `4\times10^-20N`
(c) `8\pi\times10^-20N`
(d) `4\pi\times10^-20N`
Answer (a)
NEET-2020
Question 9. A long solenoid of `50 cm` length having `100` turns carries a current of `2.5 A`. The magnetic field at the centre of the solenoid is :
`(\mu_0=4\pi\times10^-7TmA^-1)`
(a) `3.14\times10^-4T`
(b) `6.28\times10^-5T`
(c) `3.14\times10^-5T`
(d) `6.28\times10^-4T`
Answer (d)
NEET-2019
Question 10. A cylinderical conductor of radius R is carrying a constant current. The plot of the magnitude of the magnetic field. B with the distane d from the centre of the conductor, is correctly represented by the figure :
(a)
(b)
(c)
(d)
Answer (c)
Question 11. Ionized hydrogen atoms and `\alpha`-particles with same momenta enters perpendicular to a constant magnetic field, B. The ratio of their radii of their paths `r_H : r_\alpha` will be :
(a) `1:2`
(b) `4:1`
(c) `1:4`
(d) `2:1`
Answer (d)
NEET-2018
Question 12. A metallic rod of mass per unit length `0.5 kg m^–1` is lying horizontally on a smooth inclined plane which makes an angle of `30^°` with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction `0.25 T` is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is
(a) `7.14A`
(b) `5.98A`
(c) `14.76A`
(d) 11.32A
Answer (d)
(b) `5.98A`
(c) `14.76A`
(d) 11.32A
Answer (d)
Question 13. Current sensitivity of a moving coil galvanometer is `5` div/mA and its voltage sensitivity (angular deflection per unit voltage applied) is `20` div/V. The resistance of the galvanometer is
(a) `40\Omega`
(b) `25\Omega`
(c) `250\Omega`
(d) `500\Omega`
Answer (c)
NEET-2017
Question 14. An arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current `'I'` along the same direction as shown in fogure. Magnitude of force per unit length on the middle wire `'B'` is given by
(a) `{2\mu_0I^2}/{\pid}`
(b) `{\sqrt{2}\mu_0I^2}/{\pid}`
(c) `{\mu_0I^2}/{\sqrt{2}\pid}`
(d) `{\mu_0I^2}/{2\pid}`
Answer (c)
NEET-2016
Question 15. A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the centre of the loop is `B`. It is then bent into a circular coil of n turns. The magnetic field at the centre of this coil of n turns will be
(a) `nB`
(b) `n^2B`
(c) `2nB`
(d) `2n^2B`
Answer (b)
Question 16. An electron is moving in a circular path under the influence of a transverse magnetic field of `3.57\times10^-2 T`. If the value of e/m is `1.76\times10^11 C kg^-1`, the frequency of revoluation of the electron is
(a) `1GHz`
(b) `100MHz`
(c) `62.8MHz`
(d) `6.28MHz`
Answer (a)
Question 17. A long straight wire of radius `\alpha` carries a steady current `I`. The current is uniformly distributed over its cross-section. The ratio of the magnetic fields B and B', at radial distance `a/2` and `2\alpha` respectively, from the axis of the wire is
(a) `1`
(b) `4`
(c) `1/4`
(d) `1/2`
Answer (a)
Question 18. A square loop ABCD carrying a current `i`, is placed near and coplanar with a long straight conductor XY carrying a current `I`, the net force on the loop will be
(a) `{2\mu_0liL}/{3\pi}`
(b) `{\mu_0liL}/{2\pi}`
(c) `{2\mu_0li}/{3\pi}`
(d) `{\mu_0li}/{2\pi}`
Answer (c)
NEET-2015
Question 19. A proton and an alpha particle both enter a region of uniform magnetic field B, moving at right angles to the field B. If the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is `1 MeV`, the energy acquired by the alpha particle will be
(a) `1.5MeV`
(b) `1MeV`
(c) `4MeV`
(d) `0.5MeV`
Answer (b)
Question 20. An electron moving in a circular orbit of radius `r` makes `n` rotations per second. The magnetic field produced at the centre has magnitude
(a) `{\mu_0n^2e}/{r}`
(b) `{\mu_0n e}/{2r}`
(c) `{\mu_0n e}/{2\pir}`
(d) Zero
Answer (b)
Question 21. A conducting square frame of side `'a'` and a long straight wire carrying current `I` are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity `'V'`. The emf induced in the frame will be proportional to
(a) `1/{(2x+a)^2}`
(b) `1/{(2x+a)(2x-a)}`
(c) `1/x^2`
(d) `1/{(2x-a)^2}`
Answer (b)
Question 22. A wire carrying current `I` has the shape shown in adjoining figure.
Linear parts of the wire are very long and parallel to `X`-axis while semicircular protion of radius `R` is lying in `Y-Z` plane. Magtnetic field at pont `O` is
(a) `\vec{B}=-{\mu_0I}/{4\piR}(\pi\hat{i}+2\hat{k})`
(b) `\vec{B}={\mu_0I}/{4\piR}(\pi\hat{i}-2\hat{k})`
(c) `\vec{B}={\mu_0I}/{4\piR}(\pi\hat{i}+2\hat{k})`
(d) `\vec{B}=-{\mu_0I}/{4\piR}(\pi\hat{i}-2\hat{k})`
Answer (a)
NEET-2014
Question 23. Two identical long conducting wires `AOB` and `COD` are placed at right angle to each other, with one above other such that `O` is their common point for the two. The wires carry `I_1` and `I_2` currents, respectively. Point `P` is lying at distance `d` from `O` along a direction perpendicular to the plane containing the wires. The magnetic field at the point `P` will be
(a) `\mu_0/{2\pid}(I_1/I_2)`
(b) `\mu_0/{2\pid}(I_1+I_2)`
(c) `\mu_0/{2\pid}(I_1^2+I_2^2)`
(d) `\mu_0/{2\pid}(I_1^2+I_2^2)^{1/2}`
Answer (d)
Question 24. In an ammeter `0.2%` of main current passes through the galvanometer. If resistance of galvanometer is `G`, the resistance of ammeter will be
(a) `1/{499}G`
(b) `{499}/{500}G`
(c) `1/{500}G`
(d) `{500}/{499}G`
Answer (c)
NEET-2013
Question 25. A long straight wire carries a certain current and produces a magnetic field `2\times10^-4Wb m^-2` at a perpendicular distance of `5 cm` from the wire. An electron situated at `5 cm` from the wire moves with a velocity `10^7 ms^-1` towards the wire along perpendicular to it. The force experienced by the electron will be (charge on electron `1.6\times10^-19 C`)
(a) `3.2N`
(b) `3.2\times10^-16N`
(c) `1.6\times10^-16N`
(d) Zero
Answer (b)
Question 26. A circular coil ABCD carrying a current `'i'` is placed in a uniform magnetic field. If the magnetic force on the segment AB is `\vec{F}`, the force on the remaining segment BCDA is
(a) `-\vec{F}`
(b) `3\vec{F}`
(c) `-3\vec{F}`
(d) `\vec{F}`
Answer (a)
Question 27. When a proton is released from rest in a room, it starts with an initial acceleration `a_0` towards west. When it is projected towards north with a speed `v_0` it moves with an initial acceleration `3a_0` towards west. The electric and magnetic fields in the room are
(a) `{ma_0}/e` east, `{3ma_0}/{ev_0}` up
(b) `{ma_0}/e` east, `{3ma_0}/{ev_0}` down
(c) `{ma_0}/e` west, `{2ma_0}/{ev_0}` up
(d) `{ma_0}/e` west, `{2ma_0}/{ev_0}` down
Answer (d)
NEET-2012
Question 28. A proton carrying `1 MeV` kinetic energy is moving in a circular path of radius `R` in uniform magnetic field. What should be the energy of an `\alpha`-particle to describe a circle of same radius in the same field?
(a) `2MeV`
(b) `1MeV`
(c) `0.5MeV`
(d) `4MeV`
Answer (b)
Question 29. A milli voltmeter of `25` milli volt range is to be converted into an ammeter of `25` ampare range. The value (in ohm) of neccessary shunt will be
(a) `0.001`
(b) `0.01`
(c) `1`
(d) `0.05`
Answer (a)
Question 30. Two similar coils of radius `R` are lying concentrically with their planes at right angles to each other. The currents flowing in them are `I` and `2I`, respectively. The resultant magnetic field induction at the centre will be
(a) `{\sqrt{5}\mu_0I}/{2R}`
(b) `{\sqrt{5}\mu_0I}/{R}`
(c) `{\mu_0I}/{2R}`
(d) `{\mu_0I}/{R}`
Answer (a)
Question 31. An alternating electric field, of frequency `v`, is applied across the dees (radius `= R`) of a cyclotron that is being used to accelerate protons (mass` = m`). The operating magnetic field `(B)` used in the cyclotron and the kinetic energy `(K)` of the proton beam, produced by it, are given by
(a) `B={mv}/e` and `K=2m\pi^2v^2R^2`
(b) `B={2\pimv}/e` and `K=m^2\pivR^2`
(c) `B={2\pimv}/e` and `K=2m\pi^2v^2R^2`
(d) `B={mv}/e` and `K=m^2\pivR^2`
Answer (c)
NEET-2011
Question 32. Charge q is uniformly spread on a thin ring of radius `R`. The ring rotates about its axis with a uniform frequency `f Hz`. The magnitude of magnetic induction at the center of the ring is
(a) `{\mu_0qf}/{2\piR}`
(b) `{\mu_0qf}/{2R}`
(c) `{\mu_0q}/{2fR}`
(d) `{\mu_0q}/{2\pifR}`
Answer (b)
Question 33.A galvanometer of resistance, `G`, is shunted by a resistance `S` ohm. To keep the main current in the circuit unchanged, the resistance to be put in series with the galvanometer is
(a) `G/{(S+G)}`
(b) `S^2/{(S+G)}`
(c) `SG/{(S+G)}`
(d) `G^2/{(S+G)}`
Answer (d)
Question 34. A square loop, carrying a steady current `I`, is placed in a horizontal plane near a long straight conductor carrying a steady current `I_1` at a distance `d` from the conductor as shown in figure. The loop will experience
((a) a net attractive force towards the conductor
(b) a net repulsive force away from the conductor
(c) a net torque acting upward perpendicular to the horizontal plane
(d) a net torque acting downward normal to horizontal plane
Answer (a)
Question 35. A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron
Answer (b)
(a) will turn towards right of direction of motion
(b) speed will decrease
(c) speed will increase
(c) will turn towards left of direction of motion
Answer (b)
Question 36. A current carrying closed loop in the form of a right angle isosceles triangle ABC is placed in uniform magnetic field acting along AB. If the magnetic force on the arm BC is `\vec{F},` the force on the arm AC is
(a) `-\sqrt{2}\vec{F}`
(b) `-\vec{F}`
(c) `\vec{F}`
(d) `\sqrt{2}\vec{F}`
Answer (b)
NEET-2010
Question 37. A current loop consists of two identical semicircular parts each of radius R, one lying in the x-y plane and the other in x-z plane. If the current in the loop is `i`. The resultant magnetic field due to the two semicircular parts at their common centre is
(a) `{\mu_0i}/{2\sqrt{2}R}`
(b) `{\mu_0i}/{2R}`
(c) `{\mu_0i}/{4R}`
(d) `{\mu_0i}/{\sqrt{2}R}`
Answer (a)
Question 38. A particle having a mass of `10^-2 kg` carries a charge of `5\times10^-8 C`. The particle is given an initial horizontal velocity of `10^5 m s^-1` in the presence of electric field `\vec{E}` and magnetic field `\vec{B}`. To keep the particle moving in a horizontal direction, it is necessary that
(1) `\vec{B}` should be perpendicular to the direction of velocity and `\vec{E}` should be along the direction of velocity
(2) Both `\vecc{B}` and `\vec{E}` should be along the direction of velocity
(3) Both `\vec{B}` and `\vec{E}` are mutually perpendicular and perpendicular to the direction of velocity.
(4) `\vec{B}` should be along the direction of velocity and `\vec{E}` should be perpendicular to the direction of velocity
Which one of the following pairs of statements is possible ?
(a) (1) and (3)
(b) (3) and (4)
(c) (2) and (3)
(d) (2) and (4)
Answer (c)
Question 39. A closely wound solenoid of `2000` turns and area of cross-section `1.5\times10^-4 m^2` carries a current of `2.0 A`. It is suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field `5\times10^-2` tesla making an angle of `30^o` with the axis of the solenoid. The torque on the solenoid will be
(a) `3\times10^-3Nm`
(b) `1.5\times10^-3Nm`
(c) `1.5\times10^-2Nm`
(d) `3\times10^-2Nm`
Answer (c)
Question 40. Charge `q` is uniformly spread on a thin ring of radius `R`. The ring rotates about its axis with a uniform frequency `f Hz`. The magnitude of magnetic induction at the center of the ring is
(a) `{\mu_0qf}/{2\piR}`
(b) `{\mu_0qf}/{2R}`
(c) `{\mu_0q}/{2fR}`
(d) `{\mu_0q}/{2f\piR}`
Answer (b)
Question 41. A galvanometer has a coil of resistance `100 ohm` and gives a full scale deflection for `30 mA` current. If it is to work as a voltmeter of `30` volt range, the resistance required to be added will be
(a) `900\Omega`
(b) `1800\Omega`
(c) `500\Omega`
(d) `1000\Omega`
Answer (a)
Question 42. A square current carrying loop is suspended in a uniform magnetic field acting in the plane of the loop. If the force on one arm of the loop is `vecF`, the net force on the remaining three arms of the loop is
(a) `3\vec{F}`
(b) `-\vec{F}`
(c) `-3\vec{F}`
(d) `\vec{F}`
Answer (b)
NEET-2009
Question 43. The magnetic force acting on a charged particle of charge `-2\muC` in a magnetic frield of `2 T` acting in y direction, when the particle velocity is `(2\hat{i}+3\hat{}j)\times10^6ms^-1`
(a) `4N` in z-direction
(b) `8N` in y-direction
(c) `8N` in z-direction
(d) `8N` in -z-direction
Answer (d)
(b) `8N` in y-direction
(c) `8N` in z-direction
(d) `8N` in -z-direction
Answer (d)
Question 44. A galvanometer havings a coil resistance of `60 \Omega` shows full scale deflection when a current of `1.0 amp` passes through it. It can be converted into an ammeter to read currents upto `5.0 amp` by
(a) putting in series a resistance of `15\Omega`
(b) putting in series a resistance of `240\Omega`
(c) putting in parallel a resistance of `15\Omega`
(d) putting in parallel a resistance of `240\Omega`
Answer (c)
Question 45. Under the influence of a uniform magnetic field, a charged particle moves with constant speed `v` in a circle of radius `R`. The time period of rotation of the particle
(a) depends on `R` and not on `v`
(b) is independent of both `v` and `R`
(c) depends on both `v` and `R`
(d) depends on `v` and not on `R`
Answer (b)
NEET-2008
Question 46. A particle of mass `m`, charge `Q` and kinetic energy `T` enters a transverse uniform magnetic field of induction `\vec{B}`. After `3` seconds the kinetic energy of the particle will be
(a) `T`
(b) `4T`
(c) `3T`
(d) `2T`
Answer (a)
Question 47. A closed loop PQRS carrying a current is placed in a uniform magnetic field. If the magnetic forces on segments PS, SR and RQ are `F_1, F_2` and `F_3` respectively and are in the plane of the paper and along the directions shown, the force on the segment QP is
(a) `\sqrt{(F_3-F_1)^2 -F_2^2}`
(b) `F_3-F_1 +F_2`
(c) `F_3-F_1 -F_2`
(d) `\sqrt{(F_3-F_1)^2 +F_2^2}`
Answer (d)
Question 48. A galvanometer of resistance `50\Omega` is connected to a battery of `3 V` along with a resistance of `2950\Omega` in series. A full scale deflection of `30` divisions is obtained in the galvanometer. In order to reduce this deflection to `20` divisions, the resistance in series should be
(a) `6050\Omega`
(b) `4450\Omega`
(c) `5050\Omega`
(d) `5550\Omega`
Answer (b)
NEET-2007
Question 49. Under the influence of a uniform magnetic field, a charged particle moves with constant speed `v` in a circle of radius `R`. The time period of rotation of the particle
(a) depends on `R` and not on `v`
(b) is independent of both `v` and `R`
(c) depends on both `v` and `R`
(d) depends on `v` and not on `R`
Answer (b)
Question 50. The resistance of an ammeter is `13\Omega` and its scale is graduated for a current upto `100` amps. After an additional shunt has been connected to this ammeter it becomes possible to measure currents upto `750` amperes by this meter. The value of shunt-resistance is
(a) `2\Omega`
(b) `0.2\Omega`
(c) `2K\Omega`
(d) `20\Omega`
Answer (a)
NEET-2006
Question 51. Two circular coils `1` and `2` are made from the same wire but the radius of the `1^{st}` coil is twice that of the `2^{nd}` coil. What is the ratio of potential difference in volts should be applied across them so that the magnetic field at their centres is the same?
(a) `2`
(b) `3`
(c) `4`
(d) `6`
Answer (c)
Question 52. When a charged particle moving with velocity `\vec{v}` is subjected to a magnetic field of induction `\vec{B}`, the force on it is non-zero. This implies that
(a) angle between is either zero or `180^o`
(b) angle between is necessarily `90^o`
(c) angle between can have any value other than `90^o`
(d) angle between can have any value other than zero and `180^o`.
Answer (d)
NEET-2005
Question 53. An electron moves in a circular orbit with a uniform speed `v`. It producess a magnetic field `B` at the centre of the circle. The radius of the circle is proportional to
(a) `\sqrt{B/v}`
(b) `B/v`
(c) `\sqrt{v/B}`
(d) `v/B`
Answer (c)
Question 54. A very long straight wire carries a current `I`. At the instant when a charge `+Q` at point P has velocity `\vec{v}`, as shown, the force on the charge is
(a) along Oy
(b) opposite to Oy
(c) along Ox
(d) opposite to Ox
Answer (a)
NEET-2004
Question 55. A galvanometer of `50 ohm` resistance has `25` divisions. A current of `4\times10^-4` ampere gives a deflection of one division. To convert this galvanometer into a voltmeter having a range of `25` volts, it should be connected with a resistance of
(a) `2500\Omega` as a shunt
(b) `2450\Omega` as a shunt
(c) `2550\Omega` in series
(d) `2450\Omega` in series
Answer (d)
Question 56. To convert a galvanometer into a voltmeter one should connect a
(a) high resistance in series with galvanometer
(b) low resistance in series with galvanometer
(c) high resistance in parallel wilh galvanometer
(d) low resistance in parallel with galvanometer.
Answer (a)
NEET-2003
Question 57. A charged particle moves through a magnetic field in a firection perpendicular to it. Then the
(a) speed of the particle remains unchanged
(b) direction of the particle remains unchanged
(c) acceleration remains unchanged с
(d) velocity remains unchanged
Answer (a)
Question 58. A long solenoid carrying a current producess a magnetic field `B` along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is
(a) `B/2`
(b) `B`
(c) `2B`
(d) `4B`
Answer (b)
NEET-2002
Question 59. To convert a galvanometer into a voltmeter one should connect a
(a) high resistance in series with galvanometer
(b) low resistance in series with galvanometer
(c) high resistance in parallel with galvanometer
(d) low resistance in parallel with galvanometer.
Answer (a)
Question 60. A charge q moves in a region where electric field and magnetic field both exist, then force on it is
(a) `q(\vec{v}\times\vec{B})`
(b) `q\vec{E}+q(\vec{v}\times\vec{B})`
(c) `q\vec{E}+\vec{q}(\vec{B}\times\vec{v})`
(d) `q\vec{B}+\vec{q}(\vec{E}\times\vec{v})`
Answer (b)
Question 61. The magnetic field of given length of wire for single turn coil at its centre is B then its value for two turns coil for the same wire is
(a) `B/4`
(b) `B/2`
(c) `4B`
(d) `2B`
Answer (c)
NEET-2001
Question 62. If number of turns, area and current through a coil is given by `n`, A and `i` respectively then its magnetic moment will be
(a) `niA`
(b) `n^2iA`
(c) `niA^2`
(d) `{ni}/sqrt{A}`
Answer (a)
Question 63. An electron having mass `m` and kinetic energy `E` anter in uniform magnetic field `B` perpendiculaly, then its frequency will be
(a) `{eE}/{quB}`
(b) `{2\pim}/{em}`
(c) `{eB}/{2\pim}`
(d) `{2m}/{eBE}`
Answer (c)
NEET-2000
Question 64. The magnetic field at centre, P will be
(a) `\mu_0/{4\pi}`
(b) `\mu_0/\pi`
(c) `\mu_0/{2\pi}`
(d) `4\mu_0\pi`
Answer (c)
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