NEET AIPMT Physics Chapter Wise Solutions - Moving Charges and Magnetism

NEET AIPMT Physics Chapter Wise Solutions – Moving Charges and Magnetism

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NEET AIPMT Physics Chapter Wise Solutions Chemistry Biology

1. 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 (AIPMT 2015)
(a) 1.5 MeV
(b) 1 MeV
(c) 4 MeV
(d) 0.5 MeV

2. An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude (AIPMT 2015 ,Cancelled)

3. A wire carrying current I has the shape as shown in adjoining figure. Linear parts of the wire are very long and parallel to X-axis while semicircular portion of radius R is lying in Y-Z plane. Magnetic field at point O is (AIPMT 2015, Cancelled)

4. 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 (AIPMT 2015, Cancelled)

5. In an ammeter 0.2% of main current passes through the galvanometer. If resistance of galvanometer is G, the resistance of ammeter will be (AIPMT 2014)

6. 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 I₁ and I₂ currents, respectively. Point P is lyiAg at distance d from O along a direction perpendicular to the plane containing the wires. The magnetic field at the point P will be (AIPMT 2014)

7. When a proton is released from rest in a room, it starts with an initial acceleration a0 towards west. When it is projected towards north with a speed v₀ it moves with an initial acceleration 3a₀ toward west. The electric and magnetic fields in the room are (NEET 2013 )

8. A long straight wire carries a certain current and produces a magnetic field 2 × 10^-4 Wb 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 10⁷ m/s towards the wire along perpendicular to it. The force experienced by the electron will be (charge on electron 1.6 × 10^-19 C) (Karnataka NEET 2013)
(a) 3.2 N
(b) 3.2 × 10^-16N
(c) 1.6 × 10^-16N
(d) zero

9. A circular coil ABCD carrying a current “i” is placed in a uniform magnetic field. If the magnetic force on the segment AB is $\overset { \rightarrow }{ F }$ , the force on the remaining segment BCDA is (Karnataka NEET 2013)

(a) – $\overset { \rightarrow }{ F }$
(b) 3 $\overset { \rightarrow }{ F }$
(c) – 3 $\overset { \rightarrow }{ F }$
(d) $\overset { \rightarrow }{ F }$

10. 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 21, respectively. The resultant magnetic field induction at the centre will be (Prelims 2012)

11. A milli voltmeter of 25 milli volt range is to be converted into an ammeter of 25 ampere range. The value (in ohm) of necessary shunt will be (Prelims 2012)
(a) 0.001
(b) 0.01
(c) 1
(d) 0.05

12. An alternating electric field, of frequency u, 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 (A) of the proton beam, produced by it, are given by (Prelims 2012)

13. 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 a-particle to describe a circle of same radius in the same field? (Mains 2012)
(a) 2 MeV
(b) 1 MeV
(c) 0.5 MeV
(d) 4 MeV

14. A current carrying closed loop in the form of a right angle isosceles triangle ABC is placed in a uniform magnetic field acting along AB. If the magnetic force on the arm BC is F, the force on- the arm AC is (Prelims 2011)

15. 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 (Prelims 2011)
(a) will turn towards right of direction of motion
(b) speed will decrease
(c) speed will increase
(d) will turn towards left of direction of motion

16. 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 (Mains 2011)

17. Charge q is uniformly spread on a thin ring of radius R. The ring rotates about its axis with a uniform lfequency/Hz. The magnitude of magnetic induction at the center of the ring is (Mains 2011, Prelims 2010)

18. A square loop, carrying a teady current I, is placed in a horizontal plane near a long straight conductor carrying a steady current ( at a distance d from the conductor as shown in figure. The loop will experience (Mains 2011)

(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 the horizontal plane

19. A galvanometer has a coil of resistance 100 ohm and gives a lull 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 (Prelims 2010)
(a) 900 Ω
(b) 1800 Ω
(c) 500 Ω
(d) 1000 Ω

20. 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 the net force on the remaining three arms of the loop is (Prelims 2010)
(a) 3 $\overset { \rightarrow }{ F }$
(b) – $\overset { \rightarrow }{ F }$
(c) -3 $\overset { \rightarrow }{ F }$
(d) $\overset { \rightarrow }{ F }$

21. 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 (mains 2010)

22. A closely wound solenoid of 2000 turns and area of cross-section 1.5 × 10^-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 × 10^-2 tesla making an angle of 30° with the axis of the solenoid. The torque on the solenoid will be (Mains 2010)
(a) 3 × 10^-3Nm
(b) 1.5 × 10^-3Nm
(c) 1.5 × 10^-2N m
(d) 3 × 10^-2Nm

23. A particle having a mass of 10^-2 kg carries a charge of 5 × 10^-8C. The particle is given an initial horizontal velocity of 10⁵ ms^-1 in the presence of electric field £ and magnetic field B. To keep the particle moving in a horizontal direction, it is necessary that (Mains 2010)
(1) B should be perpendicular to the direction of velocity and E should be along the direction of velocity
(2) Both B and E should be along the direction of velocity
(3) Both B and E are mutually perpendicular and perpendicular to the direction of velocity.
(4) B should be along the direction of velocity and £ 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)

24. A galvanometer having a coil resistance of 60 Ω 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 (Prelims 2009)
(a) putting in series a resistance of 15 Ω
(b) putting in series a resistance of 240 Ω
(c) putting in parallel a resistance of 15 Ω
(d) putting in parallel a resistance of 240 Ω

25. The magnetic force acting on a charged particle of charge-2 µ.C in a magnetic field of 2 T acting in y direction, when the particle velocity is is (Prelims 2009)
(a) 4 N in z direction
(b) 8 N in y direction
(c) 8 N in z direction
(d) 8 N in – z direction

26. 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 (Prelims 2009, 2007)
(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

27. A particle of mass m, charge Q and kinetic energy T enters a transverse uniform magnetic field of induction j). After 3 seconds the kinetic energy of the particle will be (Prelims 2008)
(a) T
(b) 4T
(c) 3 T
(d) 2 T

28. 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 F₁ F₂ and F₃ respectively and are in the plane of the paper and along the directions shown, the force on the segment QP is (Prelims 2008)

29. A galvanometer of resistance 50 Ω is connected to a battery of 3 V along with a resistance of 2950 Ω 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 (Prelims 2008)
(a) 6050 Ω
(b) 4450 Ω
(c) 5050 Ω
(d) 5550 Ω

30. The resistance of an ammeter is 13 Ω 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 (2007)
(a) 2 Ω
(b) 0.2 Ω
(c) 2 k Ω
(d) 20 Ω

31. When a charged particle moving with velocity v is subjected to a magnetic field of induction B , the force on it is non-zero. This implies that
(a) angle between is either zero or 180°
(b) angle between is necessarily 90°
(c) angle between can have any value other than 90°
(d) angle between can have any value other than zero and 180°. (2006)

32. Two circular coils 1 and 2 are made from the same wire but the radius Of the 1st coil is twice that of the 2nd coil. What potential difference in volts should be applied across them so that the magnetic field at their centres is the same? (2006)
(a) 2
(b) 3
(c) 4
(d) 6.

33. A very long straight wire carries a current I. At the instant when a charge +Q at point P has velocity $\overset { \rightarrow }{ V }$ , as shown, the force on the charge is (2005)

34. An electron moves in a circular orbit with a uniform speed v. It produces a magnetic field 5 at the centre of the circle. The radius of the circle is proportional to (2005)

35. A galvanometer of 50 ohm resistance has 25 divisions. A current of 4 × 10^-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 (2004)
(a) 2500 Ω as a shunt
(b) 2450 Ω as a shunt
(c) 2550 Ω in series
(d) 2450 Ω in series

36. To convert a galvanometer into a voltmeter one should connect a (2004, 2002)
(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.

37. A charged particle moves through a magnetic field in a direction perpendicular to it. Then the (2003)
(a) speed of the particle remains unchanged
(b) direction of the particle remains unchanged
(c) acceleration remains unchanged
(d) velocity remains unchanged

38. A long solenoid carrying a current produces 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 (2003)
(a) B / 2
(b) B
(c) 2 B
(d) 4 B

39. A charge q moves in a region where electric field and magnetic field both exist, then force on it is (2002)

40. 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 (2002)
(a) B/4
(b) B/2
(c) 45
(d) 25.

41. If number of turns, area and current through a coil is given by n, A and i respectively then its magnetic moment will be (2001)

42. An electron having mass m and kinetic energy E enter in uniform magnetic field 5 perpendicularly, then its frequency will be (2001)

43. The magnetic field at centre, P will be (2000)

44. Magnetic field due to 0.1 A current flowing through a circular coil of radius 0.1 m and 1000 turns at the centre of the coil is (1999)
(a) 6.28 × 10^-4 T
(b) 4.31 × 10^-2 T
(c) 2 × 10^-1 T
(d) 9.81 × 10^-4 T

45. A straight wire of diameter 0.5 mm carrying a current of 1 A is replaced by the another wire of 1 mm diameter carrying the same current. The strength of the magnetic field far away is (1999, 97)
(a) one-quarter of the earlier value
(b) one-half of the earlier value
(c) twice the earlier value
(d) same as the earlier value

46. If a long hollow copper pipe carries a current, then produced magnetic field will be (1999)
(a) both inside and outside the pipe
(b) outside the pipe only
(c) inside the pipe only
(d) neither inside nor outside the pipe

47. Magnetic field intensity at the centre of coil of 50 turns, radius 0.5 m and carrying a current of 2 A, is (1999)
(a) 3 × 10^-4 T
(b) 1.25 × 10^-4 T
(c) 0.5 × 10^-5 T
(d) 4 × 10⁶ T

48. A charge having elm equal to 108 C/kg and with velocity 3 x 105 m/s enters into a uniform magnetic field B = 0.3 tesla at an angle 30° with direction of field. The radius of curvature will be (1999)
(a) 0.01 cm
(b) 0.5 cm
(c) 1 cm
(d) 2 cm.

49. Two long parallel wires are at a distance of 1 metre. Both of them carry one ampere of current. The force of attraction per unit length between the two wires is (1998)
(a) 5 × 10^-8 N/m
(b) 2 × 10^-8 N/m
(c) 2 × 10^-7 N/m
(d) 10^-7 N/m

50. A galvanometer having a resistance of 9 ohm is shunted by a wire of resistance 2 ohm. If the total current is 1 amp, the part of it passing through the shunt will be (1998)
(a) 0.2 amp
(b) 0.8 amp
(c) 0.25 amp
(d) 0.5 amp

51. A coil of one turn is made of a wire of certain length and then from the same length a coil of two turns is made. If the same current is passed in both the cases, then, the ratio of the magnetic inductions at their centres will be (1998)
(a) 4 : 1
(b) 1 : 4
(c) 2 : 1
(d) 1 : 2

52. Two parallel wires in free space are 10 cm apart and each carries a current of 10 A in the same direction. The force exerted by one wire on the other, per metre length is (1997)
(a) 2 × 10^-4N, repulsive
(b) 2 × 10^-7N, repulsive
(c) 2 × 10^-4N, attractive
(d) 2 × 10^-7N, attractive.

53. A positively charged particle moving due East enters a region of uniform magnetic field directed vertically upwards. This particle will (1997)
(a) move in a circular path with a decreased speed
(b) move in a circular path with a uniform speed
(c) get deflected in vertically upward direction
(d) move in circular path with an increased speed.

54. Tesla is the unit of (1997, 88)
(a) electric field
(b) magnetic field
(c) electric flux
(d) magnetic flux.

55. Two equal electric currents are flowing perpendicular to each other as shown in the figure. AB and CD are perpendicular to each other and symmetiically placed with respect to the currents. Where do we expect the resultant magnetic field to be zero? (1996)

(a) On CD
(b) OnAB
(c) On both OD and 80
(d) On both AB and CD

56. The magnetic field d $\overset { \rightarrow }{ B }$ due to a small current element d $\overset { \rightarrow }{ L }$ at a distance r and element carrying current i is (1996)

57. A 10 eV electron is circulating in a plane at right angles to a uniform field at magnetic induction 10^-4 Wb m² (= 1.0 gauss), the orbital radius of electron is (1996)
(a) 11 cm
(b) 18 cm
(c) 12 cm
(d) 16cm.

58. A beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength 20 Vm 1 and 0.5 T at right angles to the direction of motion of the electrons. What is the velocity of the electrons? (1996)
(a) 8 ms^-1
(b) 5.5 ms^-1
(c) 20 ms^-1
(d) 40 ms^-1.

59. A circular loop of area 0.01 m² carrying a current of 10 A, is held perpendicular to a magnetic field of intensity 0.1 T. The torque acting on the loop is (1994)
(a) 0.001 Nm
(b) 0.8 Nm
(c) zero
(d) 0.01 N m.

60. A charge moving with velocity v in X-direction is subjected to a field of magnetic induction in negative X-direction. As a result, the charge will (1993)
(a) remain unaffected
(b) start moving in a circular path Y-Z plane
(c) retard along X-axis
(d) moving along a helical path around X-axis

61. A coil carrying electric current is placed in uniform magnetic field (1993)
(a) torque is formed
(b) e.m.f is induced
(c) both (a) and (b) are correct
(d) none of these

62. To convert a galvanometer into a ammeter, one needs to connect a (1992)
(a) low resistance in parallel
(b) high resistance in parallel
(c) low resistance in series
(d) high resistance in series

63. A straight wire of length 0.5 metre and carrying a current of 1.2 ampere is placed in uniform magnetic field of induction 2 tesla. The magnetic field is perpendicular to the length of the wire. The force on the wire is (1992)
(a) 2.4 N
(b) 1.2 N
(c) 3.0 N
(d) 2.0 N

64. The magnetic field at a distance r from a long wire carrying current i is 0.4 tesla. The magnetic field at a distance 2r is (1992)
(a) 0.2 tesla
(b) 0.8 tesla
(c) 0.1 tesla
(d) 1.6 tesla

65. A uniform magnetic field acts right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of radius 2 cm. If the speed of electrons is doubled, then the radius of the circular path will be (1991)
(a) 2.0 cm
(b) 0.5 cm
(c) 4.0 cm
(d) 1.0 cm

66. A deuteron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 metre in a plane perpendicular to magnetic field B. The kinetic energy of the proton that describes a circular orbit of radius 0.5 metre in the same plane with the same B is (1991)
(a) 25 keV
(b) 50 keV
(c) 200 keV
(d) 100 keV

67. The magnetic induction at a pont point P which is at the distance of 4 cm from a tong current carrying wire is 10^-3 T. The field of induction at a distance 12 cm from the current will be (1990)
(a) 3.33 × 10^-4 T
(b) 1.11 × 10^-4 T
(c) 33 × 10^-3 T
(d) 9 × 10^-3 T

68. Energy in a current carrying coil is stored in the form of (1989)
(a) electric field only
(b) magnetic field only
(c) dielectric strength
(d) both (a) and (b)

69. A current carrying coil is subjected to a uniform magnetic field. The coil will orient so that its plane becomes (1988)
(a) inclined at 45° to the magnetic field
(b) inclined at any arbitrary angle to the magnetic field
(c) parallel to the magnetic field
(d) perpendicular to magnetic field

EXPLANATIONS

7. (d)

18. (a)

20. (b)

23. (c)

NEET AIPMT Physics Chapter Wise Solutions – Moving Charges and Magnetism

EXPLANATIONS

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