JEE Main & Advanced Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव Question Bank

done Force and Torque on a Current Carrying Conductor Total Questions - 91

• question_answer1)
  Two free parallel wires carrying currents in opposite direction [CPMT 1977; MP PMT 1993; AFMC 2002; CPMT 2003]
  A)
             Attract each other done clear
  B)
             Repel each other done clear
  C)
             Neither attract nor repel done clear
  D)
             Get rotated to be perpendicular to each other done clear
  View Solution play_arrow

• question_answer2)
  A rectangular loop carrying a current i is situated near a long straight wire such that the wire is parallel to the one of the sides of the loop and is in the plane of the loop. If a steady current I is established in wire as shown in figure, the loop will [IIT 1985; MP PET 1995; MP PMT 1995, 99; AIIMS 2003]
  A)
             Rotate about an axis parallel to the wire done clear
  B)
             Move away from the wire or towards right done clear
  C)
             Move towards the wire done clear
  D)
             Remain stationary done clear
  View Solution play_arrow

• question_answer3)
  A circular coil of radius 4 cm and of 20 turns carries a current of 3 amperes. It is placed in a magnetic field of intensity of 0.5\[weber/{{m}^{2}}\]. The magnetic dipole moment of the coil is                                    [MP PMT 2001]
  A)
             0.15 \[ampere-{{m}^{2}}\]     done clear
  B)
             0.3 \[ampere-{{m}^{2}}\] done clear
  C)
             0.45 \[ampere-{{m}^{2}}\]     done clear
  D)
             0.6 \[ampere-{{m}^{2}}\] done clear
  View Solution play_arrow

• question_answer4)
  A conducting circular loop of radius r carries a constant current i. It is placed in a uniform magnetic field \[\overrightarrow{B}\], such that \[\overrightarrow{B}\] is perpendicular to the plane of the loop. The magnetic force acting on the loop is [BIT 1992; MP PET 1994; IIT 1983; MP PMT 1999; AMU (Engg.) 2000]
  A)
             \[ir\overrightarrow{B}\]  done clear
  B)
             \[2\pi ri\overrightarrow{B}\] done clear
  C)
             Zero                                          done clear
  D)
             \[\pi ri\overrightarrow{B}\] done clear
  View Solution play_arrow

• question_answer5)
  Two thin long parallel wires separated by a distance b are carrying a current i amp each. The magnitude of the force per unit length exerted by one wire on the other is  [CPMT 1991; IIT 1986; Bihar MEE 1995; RPMT 1997; MP PET 1996; MP PMT 1994, 96, 99; UPSEAT 2001, 03]
  A)
             \[\frac{{{\mu }_{0}}{{i}^{2}}}{{{b}^{2}}}\]                     done clear
  B)
             \[\frac{{{\mu }_{0}}{{i}^{2}}}{2\pi b}\] done clear
  C)
             \[\frac{{{\mu }_{0}}i}{2\pi b}\]                                          done clear
  D)
             \[\frac{{{\mu }_{0}}i}{2\pi {{b}^{2}}}\] done clear
  View Solution play_arrow

• question_answer6)
  Through two parallel wires A and B, 10 and 2 ampere of currents are passed respectively in opposite direction. If the wire A is infinitely long and the length of the wire B is 2 m, the force on the conductor B, which is situated at 10 cm distance from A will be                       [CPMT 1988; MP PMT 1994]
  A)
             \[8\times {{10}^{-5}}N\]  done clear
  B)
             \[4\times {{10}^{-7}}N\] done clear
  C)
             \[4\times {{10}^{-5}}N\]  done clear
  D)
             \[4\pi \times {{10}^{-7}}N\] done clear
  View Solution play_arrow

• question_answer7)
  If two streams of protons move parallel to each other in the same direction, then they [MP PET 1999; AIIMS 2004]
  A)
             Do not exert any force on each other done clear
  B)
             Repel each other done clear
  C)
             Attract each other done clear
  D)
             Get rotated to be perpendicular to each other done clear
  View Solution play_arrow

• question_answer8)
  A straight wire carrying a current \[{{i}_{1}}\,amp\] runs along the axis of a circular current \[{{i}_{2}}\,amp\]. Then the force of interaction between the two current carrying conductors is
  A)
             \[\infty \]                               done clear
  B)
             Zero done clear
  C)
             \[\frac{{{\mu }_{0}}}{4\pi }\frac{2{{i}_{1}}{{i}_{2}}}{r}N/m\]              done clear
  D)
             \[\frac{2{{i}_{1}}{{i}_{2}}}{r}N/m\] done clear
  View Solution play_arrow

• question_answer9)
  Two parallel wires are carrying electric currents of equal magnitude and in the same direction. They exert                    [CPMT 1990; MP PET/PMT 1988;  Orissa JEE 2003; AFMC 2003]
  A)
             An attractive force on each other done clear
  B)
             A repulsive force on each other done clear
  C)
             No force on each other done clear
  D)
             A rotational torque on each other done clear
  View Solution play_arrow

• question_answer10)
  Two long and parallel wires are at a distance of 0.1 m and a current of 5 A is flowing in each of these wires. The force per unit length due to these wires will be          [CPMT 1977]
  A)
             \[5\times {{10}^{-5}}\,N/m\] done clear
  B)
             \[5\times {{10}^{-3}}\,N/m\] done clear
  C)
             \[2.5\times {{10}^{-5}}\,N/m\]                                         done clear
  D)
             \[2.5\times {{10}^{-4}}\,N/m\] done clear
  View Solution play_arrow

• question_answer11)
  Two straight parallel wires, both carrying 10 ampere in the same direction attract each other with a force of\[1\times {{10}^{-3}}N\]. If both currents are doubled, the force of attraction will be [MP PET 1994]
  A)
             \[1\times {{10}^{-3}}\,N\]       done clear
  B)
             \[2\times {{10}^{-3}}\,N\] done clear
  C)
             \[4\times {{10}^{-3}}\,N\]       done clear
  D)
             \[0.25\times {{10}^{-3}}\,N\] done clear
  View Solution play_arrow

• question_answer12)
  A circular coil of radius 4 cm has 50 turns. In this coil a current of 2 A is flowing. It is placed in a magnetic field of 0.1 \[weber/{{m}^{2}}\]. The amount of  work done in rotating it through \[180{}^\circ \] from its equilibrium position will be [CPMT 1977]
  A)
             0.1 J                                          done clear
  B)
             0.2 J done clear
  C)
             0.4 J                                          done clear
  D)
             0.8 J done clear
  View Solution play_arrow

• question_answer13)
  3 A of current is flowing in a linear conductor having a length of 40 cm. The conductor is placed in a magnetic field of strength 500 gauss and makes an angle of \[30{}^\circ \] with the direction of the field. It experiences a force of magnitude [MP PET 1993]
  A)
             \[3\times {{10}^{4}}\,newton\]                                        done clear
  B)
             \[3\times {{10}^{2}}\,newton\] done clear
  C)
             \[3\times {{10}^{-2}}\,newton\]                                      done clear
  D)
             \[3\times {{10}^{-4}}\,newton\] done clear
  View Solution play_arrow

• question_answer14)
  The radius of a circular loop is r and a current i  is flowing in it. The equivalent magnetic moment will be [CPMT 1990]
  A)
             ir     done clear
  B)
             \[2\pi ir\] done clear
  C)
             \[i\pi {{r}^{2}}\]                   done clear
  D)
             \[\frac{1}{{{r}^{2}}}\] done clear
  View Solution play_arrow

• question_answer15)
  A current carrying loop is placed in a uniform magnetic field. The torque acting on it does not depend upon [CPMT 1985; RPMT 1997; Kerala PMT 2002]
  A)
             Shape of the loop               done clear
  B)
             Area of the loop done clear
  C)
             Value of the current          done clear
  D)
             Magnetic field done clear
  View Solution play_arrow

• question_answer16)
  To make the field radial in a moving coil galvanometer [MP PET 1993]
  A)
             The number of turns in the coil is increased done clear
  B)
             Magnet is taken in the form of horse-shoe done clear
  C)
             Poles are cylindrically cut done clear
  D)
             Coil is wounded on aluminium frame done clear
  View Solution play_arrow

• question_answer17)
  The deflection in a moving coil galvanometer is [MP PMT 1993]
  A)
             Directly proportional to the torsional constant done clear
  B)
             Directly proportional to the number of turns in the coil done clear
  C)
             Inversely proportional to the area of the coil done clear
  D)
             Inversely proportional to the current flowing done clear
  View Solution play_arrow

• question_answer18)
  A moving coil sensitive galvanometer gives at once much more deflection. To control its speed of deflection [MP PET 1985]
  A)
             A high resistance is to be connected across its terminals done clear
  B)
             A magnet should be placed near the coil done clear
  C)
             A small copper wire should be connected across its terminals done clear
  D)
             The body of galvanometer should be earthed done clear
  View Solution play_arrow

• question_answer19)
  In a moving coil galvanometer, the deflection of the coil \[\theta \] is related to the electrical current i by the relation                          [MP PMT 1996, 2000, 03; RPMT 1997; CPMT 1975; MP PET 1999]
  A)
             \[i\propto \tan \theta \]  done clear
  B)
             \[i\propto \theta \] done clear
  C)
             \[i\propto {{\theta }^{2}}\]    done clear
  D)
             \[i\propto \sqrt{\theta }\] done clear
  View Solution play_arrow

• question_answer20)
  The unit of electric current ?ampere? is the current which when flowing through each of two parallel wires spaced 1 m apart in vacuum and of infinite length will give rise to a force between them equal to [BIT 1987; CBSE PMT1998; MP PET 1999; MP PMT 2002]
  A)
             \[1\,N/m\]                             done clear
  B)
             \[2\times {{10}^{-7}}\,N/m\] done clear
  C)
             \[1\times {{10}^{-2}}\,N/m\] done clear
  D)
             \[4\pi \times {{10}^{-7}}\,N/m\] done clear
  View Solution play_arrow

• question_answer21)
  A moving coil galvanometer has N number of turns in a coil of effective area A, it carries a current I. The magnetic field B is radial. The torque acting on the coil is      [MP PMT 1994]
  A)
             \[N{{A}^{2}}{{B}^{2}}I\]   done clear
  B)
             \[NAB{{I}^{2}}\] done clear
  C)
             \[{{N}^{2}}ABI\]                  done clear
  D)
             NABI done clear
  View Solution play_arrow

• question_answer22)
  A small coil of N turns has an effective area A and carries a current I. It is suspended in a horizontal magnetic field \[\overrightarrow{B}\] such that its plane is perpendicular to \[\overrightarrow{B}\]. The work done in rotating it by \[180{}^\circ \] about the vertical axis is [MP PMT 1994]
  A)
             NAIB                                         done clear
  B)
             2NAIB done clear
  C)
             \[2\pi NAIB\]                        done clear
  D)
             \[4\pi NAIB\] done clear
  View Solution play_arrow

• question_answer23)
  A small coil of N turns has area A and a current I flows through it. The magnetic dipole moment of this coil will be [MP PMT 1994]
  A)
             \[NI/A\]                                  done clear
  B)
             \[N{{I}^{2}}A\] done clear
  C)
             \[{{N}^{2}}AI\]                     done clear
  D)
             NIA done clear
  View Solution play_arrow

• question_answer24)
  A current of 10 ampere is flowing in a wire of length 1.5 m. A force of 15 N acts on it when it is placed in a uniform magnetic field of 2 tesla. The angle between the magnetic field and the direction of the current is            [MP PMT 1994]
  A)
             \[30{}^\circ \]                       done clear
  B)
             \[45{}^\circ \] done clear
  C)
             \[60{}^\circ \]                       done clear
  D)
             \[90{}^\circ \] done clear
  View Solution play_arrow

• question_answer25)
  A rectangular loop carrying a current i is placed in a uniform magnetic field B. The area enclosed by the loop is A. If there are n turns in the loop, the torque acting on the loop is given by                                                   [MP PMT 1994]
  A)
             \[ni\,\overrightarrow{A}\times \overrightarrow{B}\]          done clear
  B)
             \[ni\,\overrightarrow{A}\cdot \overrightarrow{B}\] done clear
  C)
             \[\frac{1}{n}(i\overrightarrow{A}\times \overrightarrow{B})\]        done clear
  D)
             \[\frac{1}{n}(i\overrightarrow{A}\cdot \overrightarrow{B})\] done clear
  View Solution play_arrow

• question_answer26)
  An electron moves with a constant speed v along a circle of radius r. Its magnetic moment will be (e is the electron's charge)                                                       [MP PMT 1994]
  A)
             evr done clear
  B)
             \[\frac{1}{2}evr\] done clear
  C)
             \[\pi {{r}^{2}}ev\]               done clear
  D)
             \[2\pi rev\] done clear
  View Solution play_arrow

• question_answer27)
  Four wires each of length 2.0 metres are bent into four loops P, Q, R and S and then suspended into uniform magnetic field. Same current is passed in each loop. Which statement is correct                    [MP PET 1995; DPMT 1999]
  A)
             Couple on loop P will be the highest done clear
  B)
             Couple on loop Q will be the highest done clear
  C)
             Couple on loop R will be the highest done clear
  D)
             Couple on loop S will be the highest done clear
  View Solution play_arrow

• question_answer28)
  A current carrying rectangular coil is placed in a uniform magnetic field. In which orientation, the coil will not tend to rotate                                                         [MP PMT 1995]
  A)
             The magnetic field is parallel to the plane of the coil done clear
  B)
             The magnetic field is perpendicular to the plane of the coil done clear
  C)
             The magnetic field is at 45o with the plane of the coil done clear
  D)
             Always in any orientation done clear
  View Solution play_arrow

• question_answer29)
  A current carrying circular loop is freely suspended by a long thread. The plane of the loop will point in the direction [MP PMT 1995]
  A)
             Wherever left free done clear
  B)
             North-south done clear
  C)
             East-west done clear
  D)
             At \[45{}^\circ \] with the east-west direction done clear
  View Solution play_arrow

• question_answer30)
  A current carrying loop is free to turn in a uniform magnetic field. The loop will then come into equilibrium when its plane is inclined at                    [CBSE PMT 1992; Haryana CEE 1996]
  A)
             \[0{}^\circ \] to the direction of the field done clear
  B)
             \[45{}^\circ \] to the direction of the field done clear
  C)
             \[90{}^\circ \] to the direction of the field done clear
  D)
             \[135{}^\circ \] to the direction of the field done clear
  View Solution play_arrow

• question_answer31)
  The expression for the torque acting on a coil having area of cross-section A, number of turns n, placed in a magnetic field of strength B, making an angle \[\theta \] with the normal to the plane of the coil, when a current i is flowing in it, will be [MP PET 1996]
  A)
             \[ni\,AB\tan \theta \]       done clear
  B)
             \[ni\,AB\cos \theta \] done clear
  C)
             \[ni\,AB\sin \theta \]        done clear
  D)
             \[ni\,AB\] done clear
  View Solution play_arrow

• question_answer32)
  The pole pieces of the magnet used in a pivoted coil galvanometer are                                  [MP PET 1996]
  A)
             Plane surfaces of a bar magnet done clear
  B)
             Plane surfaces of a horse-shoe magnet done clear
  C)
             Cylindrical surfaces of a bar magnet done clear
  D)
             Cylindrical surfaces of a horse-shoe magnet done clear
  View Solution play_arrow

• question_answer33)
  The sensitiveness of a moving coil galvanometer can be increased by decreasing                                              [MP PMT 1996]
  A)
             The number of turns in the coil done clear
  B)
             The area of the coil done clear
  C)
             The magnetic field done clear
  D)
             The couple per unit twist of the suspension done clear
  View Solution play_arrow

• question_answer34)
  A metallic loop is placed in a magnetic field. If a current is passed through it, then                                             [UPSEAT 2003]
  A)
             The ring will feel a force of attraction done clear
  B)
             The ring will feel a force of repulsion done clear
  C)
             It will move to and fro about its centre of gravity done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer35)
  Two parallel conductors A and B of equal lengths carry currents I and 10 I, respectively, in the same direction. Then                   [MP PET 2003]
  A)
             A and B will repel each other with same force done clear
  B)
             A and B will attract each other with same force done clear
  C)
             A will attract B, but B will repel A done clear
  D)
             A and B will attract each other with different forces done clear
  View Solution play_arrow

• question_answer36)
  Three long, straight and parallel wires carrying currents are arranged as shown in figure. The force experienced by 10 cm length of wire Q is                                               [MP PET 1997]
  A)
             \[1.4\times {{10}^{-4}}N\] towards the right done clear
  B)
             \[1.4\times {{10}^{-4}}N\] towards the left done clear
  C)
             \[2.6\times {{10}^{-4}}N\] to the right done clear
  D)
             \[2.6\times {{10}^{-4}}N\] to the left done clear
  View Solution play_arrow

• question_answer37)
  A 100 turns coil shown in figure carries a current of 2 amp in a magnetic field \[B=0.2\,Wb/{{m}^{2}}\]. The torque acting on the coil is                                                     [MP PET 1997]
  A)
             0.32 Nm tending to rotate the side AD out of the page done clear
  B)
             0.32 Nm tending to rotate the side AD into the page done clear
  C)
             0.0032 Nm tending to rotate the side AD out of the page done clear
  D)
             0.0032 Nm tending to rotate the side AD into the page done clear
  View Solution play_arrow

• question_answer38)
  A current of 5 ampere is flowing in a wire of length 1.5 metres. A force of 7.5 N acts on it when it is placed in a uniform magnetic field of 2 Tesla. The angle between the magnetic field and the direction of the current is [MP PET 1997; Pb. PET 2003]
  A)
             \[30{}^\circ \]                       done clear
  B)
             45° done clear
  C)
             60° done clear
  D)
             90° done clear
  View Solution play_arrow

• question_answer39)
  A conductor in the form of a right angle ABC with AB = 3 cm and BC = 4 cm carries a current of 10 A. There is a uniform magnetic field of 5 T perpendicular to the plane of the conductor. The force on the conductor will be [MP PMT 1997]
  A)
             1.5 N                                         done clear
  B)
             2.0 N done clear
  C)
             2.5 N                                         done clear
  D)
             3.5 N done clear
  View Solution play_arrow

• question_answer40)
  The coil of a galvanometer consists of 100 turns and effective area of 1 square cm. The restoring couple is \[{{10}^{-8}}\,N-m/radian\]. The magnetic field between the pole pieces is 5 T. The current sensitivity of this galvanometer will be                                                                                    [MP PMT 1997]
  A)
             \[5\times {{10}^{4}}\,rad/\mu \,amp\]                         done clear
  B)
             \[5\times {{10}^{-6}}\,per\,amp\] done clear
  C)
             \[2\times {{10}^{-7}}\,per\,amp\]                                   done clear
  D)
             \[5\,rad/\mu \,amp\] done clear
  View Solution play_arrow

• question_answer41)
  A rectangular coil \[20\,cm\times 20\,cm\] has 100 turns and carries a current of 1 A. It is placed in a uniform magnetic field       B =0.5 T with the direction of magnetic field parallel to the plane of the coil. The magnitude of the torque required to hold this coil in this position is                                                             [MP PMT 1997]
  A)
             Zero                                          done clear
  B)
             200 N-m done clear
  C)
             2 N-m                                       done clear
  D)
             10 N-m done clear
  View Solution play_arrow

• question_answer42)
  If a current is passed in a spring, it  [MP PMT/PET 1998; AIEEE 2002]
  A)
             Gets compressed               done clear
  B)
             Gets expanded done clear
  C)
             Oscillates                                done clear
  D)
             Remains unchanged done clear
  View Solution play_arrow

• question_answer43)
  A current carrying small loop behaves like a small magnet. If A be its area and M its magnetic moment, the current in the loop will be  [MP PMT/PET 1998; RPET 2001; MP PMT 2003]
  A)
             \[M/A\]                                  done clear
  B)
             \[A/M\] done clear
  C)
             MA done clear
  D)
             \[{{A}^{2}}M\] done clear
  View Solution play_arrow

• question_answer44)
  In hydrogen atom, the electron is making \[6.6\times {{10}^{15}}\,rev/\sec \] around the nucleus in an orbit of radius 0.528 Å. The magnetic moment \[(A-{{m}^{2}})\] will be [MP PET 1999]
  A)
             \[1\times {{10}^{-15}}\]   done clear
  B)
             \[1\times {{10}^{-10}}\] done clear
  C)
             \[1\times {{10}^{-23}}\]   done clear
  D)
             \[1\times {{10}^{-27}}\] done clear
  View Solution play_arrow

• question_answer45)
  A triangular loop of side l carries a current I. It is placed in a magnetic field B such that the plane of the loop is in the direction of B. The torque on the loop is          [MP PET 2003]
  A)
             Zero                                          done clear
  B)
             IBl done clear
  C)
             \[\frac{\sqrt{3}}{2}I{{l}^{2}}{{B}^{2}}\]                          done clear
  D)
             \[\frac{\sqrt{3}}{4}IB{{l}^{2}}\] done clear
  View Solution play_arrow

• question_answer46)
  Three long, straight and parallel wires carrying currents are arranged as shown in the figure. The wire C which carries a current of 5.0 amp is so placed that it experiences no force. The distance of wire C from wire D is then               [AMU 1995]
  A)
             9 cm                                          done clear
  B)
             7 cm done clear
  C)
             5 cm                                          done clear
  D)
             3 cm done clear
  View Solution play_arrow

• question_answer47)
  A vertical wire carrying a current in the upward direction is placed in horizontal magnetic field directed towards north. The wire will experience a force directed towards [SCRA 1994]
  A)
             North                                       done clear
  B)
             South done clear
  C)
             East                                           done clear
  D)
             West done clear
  View Solution play_arrow

• question_answer48)
  A coil carrying electric current is placed in uniform magnetic field, then                                   [CBSE PMT 1993]
  A)
             Torque is formed done clear
  B)
             E.M.f. is induced done clear
  C)
             Both (a) and (b) are correct done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer49)
  A circular loop carrying a current is replaced by an equivalent magnetic dipole. A point on the axis of the loop is                                                                       [MNR 1998]
  A)
             An end-on position            done clear
  B)
             A broad side-on position done clear
  C)
             Both (a) and (b)                   done clear
  D)
             Neither (a) nor (b) done clear
  View Solution play_arrow

• question_answer50)
  A power line lies along the east-west direction and carries a current of 10 ampere. The force per metre due to the earth's magnetic field of \[{{10}^{-4}}\,tesla\] is                                                [Roorkee 1992]
  A)
             \[{{10}^{-5}}N\]                   done clear
  B)
             \[{{10}^{-4}}N\] done clear
  C)
             \[{{10}^{-3}}N\]                   done clear
  D)
             \[{{10}^{-2}}N\] done clear
  View Solution play_arrow

• question_answer51)
  A straight wire of length 0.5 metre and carrying a current of 1.2 ampere placed in a uniform magnetic field of induction 2 Tesla. The magnetic field is perpendicular to the length of the wire. The force on the wire is            [CBSE PMT 1992; BHU 1998; DPMT 2001; RPET 2003]
  A)
             2.4 N                                         done clear
  B)
             1.2 N done clear
  C)
             3.0 N                                         done clear
  D)
             2.0 N done clear
  View Solution play_arrow

• question_answer52)
  Two parallel wires in free space are 10 cm apart and each carries a current of 10 A in the same direction. The force one wire exerts on the other per metre of length is                    [CBSE PMT 1997; AFMC 1999]
  A)
             \[2\times {{10}^{-4}}N\], attractive                                done clear
  B)
             \[2\times {{10}^{-4}}N\], repulsive done clear
  C)
             \[2\times {{10}^{-7}}N\], attractive                                done clear
  D)
             \[2\times {{10}^{-7}}N\], repulsive done clear
  View Solution play_arrow

• question_answer53)
  The current sensitivity of a moving coil galvanometer can be increased by                                            [Roorkee 1999]
  A)
             Increasing the magnetic field of the permanent magnet    done clear
  B)
             Increasing the area of the deflecting coil done clear
  C)
             Increasing the number of turns in the coil done clear
  D)
             Increasing the restoring couple of the coil done clear
  View Solution play_arrow

• question_answer54)
  A circular coil of diameter 7cm has 24 turns of wire carrying current of 0.75A. The magnetic moment of the coil is [AMU (Med.) 1999]
  A)
             \[6.9\times {{10}^{-2}}amp-{{m}^{2}}\]                        done clear
  B)
             \[2.3\times {{10}^{-2}}amp\text{-}\,{{m}^{2}}\] done clear
  C)
             \[{{10}^{-2}}amp-{{m}^{2}}\] done clear
  D)
                  \[{{10}^{-3}}amp-{{m}^{2}}\] done clear
  View Solution play_arrow

• question_answer55)
  Two long parallel wires carrying equal current separated by 1m, exert a force of \[2\times {{10}^{-7}}N/m\] on one another. The current flowing through them is                                      [AMU (Engg.) 1999]
  A)
             2.0 A                                         done clear
  B)
             \[2.0\times {{10}^{-7}}A\] done clear
  C)
             1.0 A                                         done clear
  D)
             \[1.0\times {{10}^{-7}}A\] done clear
  View Solution play_arrow

• question_answer56)
  Two parallel beams of electrons moving in the same direction produce a mutual force    [MP PET 1996; DCE 1999]
  A)
             Of attraction in plane of paper done clear
  B)
             Of repulsion in plane of paper  done clear
  C)
             Upwards perpendicular to plane of paper done clear
  D)
             Downwards perpendicular to plane of paper done clear
  View Solution play_arrow

• question_answer57)
  A circular loop of area \[0.01{{m}^{2}}\] carrying a current of 10 A, is held perpendicular to a magnetic field of intensity 0.1T. The torque acting on the loop is                                                                     [Pb. PMT 2000]
  A)
             Zero                                          done clear
  B)
             0.01 N-m done clear
  C)
             0.001 N-m                              done clear
  D)
             0.8 N-m done clear
  View Solution play_arrow

• question_answer58)
  Magnetic dipole moment of a rectangular loop is  [RPET 2000]
  A)
             Inversely proportional to current in loop done clear
  B)
             Inversely proportional to area of loop done clear
  C)
             Parallel to plane of loop and proportional to area of loop   done clear
  D)
             Perpendicular to plane of loop and proportional to area of loop done clear
  View Solution play_arrow

• question_answer59)
  If m is magnetic moment and B is the magnetic field, then the torque is given by                                               [DCE 2000]
  A)
             \[\overset{\to \,\,\to }{\mathop{m.B}}\,\]                 done clear
  B)
             \[\frac{\overset{\to }{\mathop{|m|}}\,}{\overset{\to }{\mathop{|B|}}\,}\] done clear
  C)
             \[\overset{\to \,\,\,\,\to }{\mathop{m\times B}}\,\]           done clear
  D)
             \[\overset{\to \,\,\,\,\,\,\,\,\,\,\to }{\mathop{|m|.\,|B|}}\,\] done clear
  View Solution play_arrow

• question_answer60)
  What is the net force on the square coil  [DCE 2000; RPMT 2000]
  A)
             \[25\times {{10}^{-7}}N\] moving towards wire done clear
  B)
             \[25\times {{10}^{-7}}N\] moving away from wire done clear
  C)
             \[35\times {{10}^{-7}}N\] moving towards wire done clear
  D)
             \[35\times {{10}^{-7}}N\] moving away from wire done clear
  View Solution play_arrow

• question_answer61)
  Two long parallel copper wires carry currents of 5A each in opposite directions. If the wires are separated by a distance of 0.5m, then the force between the two wires is [EAMCET (Engg.) 2000]
  A)
             \[{{10}^{-5}}N,\,\]attractive  done clear
  B)
             \[{{10}^{-5}}N,\,\]repulsive done clear
  C)
             \[2\times {{10}^{-5}}N,\,\]attractive                              done clear
  D)
             \[2\times {{10}^{-5}}N,\,\]repulsive done clear
  View Solution play_arrow

• question_answer62)
  In order to increase the sensitivity of a moving coil galvanometer, one should decrease [MP PMT 2000]
  A)
             The strength of its magnet     done clear
  B)
             The torsional constant of its suspension done clear
  C)
             The number of turns in its coil                                           done clear
  D)
             The area of its coil done clear
  View Solution play_arrow

• question_answer63)
  A circular loop has a radius of 5 cm and it is carrying a current of 0.1 amp. Its magnetic moment is              [MP PMT 2000]
  A)
             \[1.32\times {{10}^{-4}}amp-{{m}^{2}}\] done clear
  B)
             \[2.62\times {{10}^{-4}}amp\text{-}{{m}^{2}}\] done clear
  C)
             \[5.25\times {{10}^{-4}}amp\text{-}{{m}^{2}}\] done clear
  D)
                  \[7.85\times {{10}^{-4}}amp\text{-}{{m}^{2}}\] done clear
  View Solution play_arrow

• question_answer64)
  Due to the flow of current in a circular loop of radius R, the magnetic induction produced at the centre of the loop is B. The magnetic moment of the loop is \[({{\mu }_{0}}=\text{permeability}\,\text{constant)}\]                                [MP PET 2000]
  A)
             \[B{{R}^{3}}/2\pi {{\mu }_{0}}\]                                       done clear
  B)
             \[2\pi B{{R}^{3}}/{{\mu }_{0}}\] done clear
  C)
             \[B{{R}^{2}}/2\pi {{\mu }_{0}}\]                                       done clear
  D)
             \[2\pi B{{R}^{2}}/{{\mu }_{0}}\] done clear
  View Solution play_arrow

• question_answer65)
  The magnetic moment of a circular coil carrying current is  [MP PET 2000]
  A)
             Directly proportional to the length of the wire in the coil    done clear
  B)
             Inversely proportional to the length of the wire in the coil done clear
  C)
             Directly proportional to the square of the length of the wire in the coil done clear
  D)
             Inversely proportional to the square of the length of the wire in the coil done clear
  View Solution play_arrow

• question_answer66)
  A long wire A carries a current of 10 amp. Another long wire B, Which is parallel to A and separated by 0.1m from A, carries a current of 5 amp, in the opposite direction to that in A. what is the magnitude and nature of the force experienced per unit length of B  \[({{\mu }_{0}}=4\pi \times {{10}^{-7}}\,weber/amp\text{-}m)\]                              [MP PET 2000]
  A)
             Repulsive force of \[{{10}^{-4}}N/m\] done clear
  B)
             Attractive force of \[{{10}^{-4}}N/m\] done clear
  C)
             Repulsive force of \[2\pi \times {{10}^{-5}}N/m\] done clear
  D)
             Attractive force of \[2\pi \times {{10}^{-5}}N/m\] done clear
  View Solution play_arrow

• question_answer67)
  A stream of electrons is projected horizontally to the right. A straight conductor carrying a current is supported parallel to electron stream and above it. If the current in the conductor is from left to right then what will be the effect on electron stream                                                         [Roorkee 2000]
  A)
             The electron stream will be pulled upward done clear
  B)
             The electron stream will be pulled downward done clear
  C)
             The electron stream will be retarted done clear
  D)
             The electron beam will be speeded up towards the right done clear
  View Solution play_arrow

• question_answer68)
  The relation between voltage sensitivity (\[{{\sigma }_{V}}\]) and current sensitivity \[({{\sigma }_{i}})\] of a moving coil galvanometer is (Resistance of Galvanometer = G)                                  [CPMT 2001]
  A)
             \[\frac{{{\sigma }_{i}}}{G}={{\sigma }_{V}}\]              done clear
  B)
             \[\frac{{{\sigma }_{_{V}}}}{G}={{\sigma }_{i}}\] done clear
  C)
             \[\frac{G}{{{\sigma }_{V}}}={{\sigma }_{i}}\]              done clear
  D)
             \[\frac{G}{{{\sigma }_{i}}}={{\sigma }_{V}}\] done clear
  View Solution play_arrow

• question_answer69)
  What is shape of magnet in moving coil galvanometer to make the radial magnetic field                                 [RPET 2001]
  A)
             Concave                                  done clear
  B)
             Horse shoe magnet done clear
  C)
             Convex                                    done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer70)
  If a wire of length 1 meter placed in uniform magnetic field 1.5 Tesla at angle \[{{30}^{o}}\] with magnetic field. The current in a wire 10 amp. Then force on a wire will be [RPET 2001]
  A)
             7.5 N                                         done clear
  B)
             1.5 N done clear
  C)
             0.5 N                                         done clear
  D)
             2.5 N done clear
  View Solution play_arrow

• question_answer71)
  A current i flows in a circular coil of radius r. If the coil is placed in a uniform magnetic field B with its plane parallel to the field, magnitude of the torque that acts on the coil is  [MP PET 2001]
  A)
             Zero                                          done clear
  B)
             \[2\pi \,r\,i\,B\] done clear
  C)
             \[\pi \,{{r}^{2}}\,i\,B\]       done clear
  D)
             \[2\pi \,{{r}^{2}}\,i\,B\] done clear
  View Solution play_arrow

• question_answer72)
  An arbitrary shaped closed coil is made of a wire of length L and a current I ampere is flowing in it. If the plane of the coil is perpendicular to magnetic field \[\overset{\to }{\mathop{B}}\,\], the force on the coil is [MP PMT 2001]
  A)
             Zero                                          done clear
  B)
             IBL done clear
  C)
             2IBL                                           done clear
  D)
             \[\frac{1}{2}IBL\] done clear
  View Solution play_arrow

• question_answer73)
  A circular coil having N turns is made from a wire of length L meter. If a current I ampere is passed through it and is placed in a magnetic field of B Tesla, the maximum torque on it is                                             [MP PMT 2001]
  A)
             Directly proportional to N done clear
  B)
             Inversely proportional to N done clear
  C)
             Inversely proportional to \[{{N}^{2}}\] done clear
  D)
             Independent of N done clear
  View Solution play_arrow

• question_answer74)
  A small cylindrical soft iron piece is kept in a galvanometer so that                                            [MP PMT 2001]
  A)
             A radial uniform magnetic field is produced done clear
  B)
             A uniform magnetic field is produced done clear
  C)
             There is a steady deflection of the coil done clear
  D)
             All of these done clear
  View Solution play_arrow

• question_answer75)
  A, B and C are parallel conductors of equal length carrying currents I, I and 2I respectively. Distance between A and B is x. Distance between B and C is also x. \[{{F}_{1}}\] is the force exerted by B on A and F2 is the force exerted by B on A choose the correct answer                            [Kerala PET 2001]
  A)
             \[{{F}_{1}}=2{{F}_{2}}\]    done clear
  B)
             \[{{F}_{2}}=2{{F}_{1}}\] done clear
  C)
             \[{{F}_{1}}={{F}_{2}}\]      done clear
  D)
             \[{{F}_{1}}=-{{F}_{2}}\] done clear
  View Solution play_arrow

• question_answer76)
  A straight conductor carries a current of 5A. An electron travelling with a speed of \[5\times {{10}^{6}}m{{s}^{-1}}\]parallel to the wire at a distance of 0.1m from the conductor, experiences a force of                                                                   [Kerala PET 2001]
  A)
             \[8\times {{10}^{-20}}N\]        done clear
  B)
             \[3.2\times {{10}^{-19}}N\] done clear
  C)
             \[8\times {{10}^{-18}}N\]        done clear
  D)
             \[1.6\times {{10}^{-19}}N\] done clear
  View Solution play_arrow

• question_answer77)
  Two galvanometers A and B require 3mA and 5mA respectively to produce the same deflection of 10 divisions. Then                                                                        [Kerala PET 2001]
  A)
             A is more sensitive than B done clear
  B)
             B is more sensitive than A done clear
  C)
             A and B are equally sensitive done clear
  D)
             Sensitiveness of B is 5/3 times that of A done clear
  View Solution play_arrow

• question_answer78)
  Two long straight parallel conductors separated by a distance of 0.5m carry currents of 5A and 8A in the same direction. The force per unit length experienced by each other is                                  [Kerala (Med.) 2002]
  A)
             \[1.6\times {{10}^{-5}}N\] (attractive)                           done clear
  B)
             \[1.6\times {{10}^{-5}}N\] (repulsive) done clear
  C)
             \[16\times {{10}^{-5}}N\] (attractive)                            done clear
  D)
             \[16\times {{10}^{-5}}N\] (repulsive) done clear
  View Solution play_arrow

• question_answer79)
  If the current is doubled, the deflection is also doubled in [Orissa JEE 2002]
  A)
             A tangent galvanometer done clear
  B)
             A moving coil galvanometer done clear
  C)
             Both (a) and (b) done clear
  D)
             None of these done clear
  View Solution play_arrow

• question_answer80)
  Which is a vector quantity                                         [AFMC 2003]
  A)
             Density                                    done clear
  B)
             Magnetic flux done clear
  C)
             Intensity of magnetic field      done clear
  D)
             Magnetic potential done clear
  View Solution play_arrow

• question_answer81)
  There long straight wires A, B and C are carrying current as shown figure. Then the resultant force on B is directed ..... [KCET 2004]
  A)
             Towards A done clear
  B)
             Towards C done clear
  C)
             Perpendicular to the plane of paper and outward done clear
  D)
             Perpendicular to the plane of paper and inward done clear
  View Solution play_arrow

• question_answer82)
  Two long conductors, separated by a distance d carry current I1 and I2 in the same direction. They exert a force F on each other. Now the current in one of them is increased to two times and its directions is reversed. The distance is also increased to 3d. The new value of the force between them is                                           [AIEEE 2004]
  A)
             ? 2F                                           done clear
  B)
             F/3 done clear
  C)
             2F/3                                          done clear
  D)
             ? F/3 done clear
  View Solution play_arrow

• question_answer83)
  The resultant magnetic moment of neon atom will be  [J & K CET 2004]
  A)
             Infinity                                     done clear
  B)
             mB done clear
  C)
             Zero                                          done clear
  D)
             mB/2 done clear
  View Solution play_arrow

• question_answer84)
  A one metre long wire is lying at right angles to the magnetic field. A force of 1 kg wt. is acting on it in a magnetic field of 0.98 Tesla. The current flowing in it will be [J & K CET 2004]
  A)
             100 A                                        done clear
  B)
             10 A done clear
  C)
             1 A done clear
  D)
             Zero done clear
  View Solution play_arrow

• question_answer85)
  A beam of electrons and protons move parallel to each other in the same direction, then they   [DCE 2004]
  A)
             Attract each other              done clear
  B)
             Repel each other done clear
  C)
             No relation                            done clear
  D)
             Neither attract nor repel done clear
  View Solution play_arrow

• question_answer86)
  Two parallel wires of length 9 m each are separated by a distance 0.15 m. If they carry equal currents in the same direction and exerts a total force of 30 ´ 10?7 N on each other, then the value of current must be              [MH CET 2003]
  A)
             2.5 amp                                   done clear
  B)
             3.5 amp done clear
  C)
             1.5 amp                                   done clear
  D)
             0.5 amp done clear
  View Solution play_arrow

• question_answer87)
  Current i is carried in a wire of length L. If the wire is turned into a circular coil, the maximum magnitude of torque in a given magnetic field B will be                                 [Pb. PET 2004]
  A)
             \[\frac{Li{{B}^{2}}}{2}\]    done clear
  B)
             \[\frac{L{{i}^{2}}B}{2}\] done clear
  C)
             \[\frac{{{L}^{2}}iB}{4\pi }\]     done clear
  D)
             \[\frac{L{{i}^{2}}B}{4\pi }\] done clear
  View Solution play_arrow

• question_answer88)
  In ballistic galvanometer, the frame on which the coil is wound is non-metallic to                                              [MH CET 2004]
  A)
             Avoid the production of induced e.m.f. done clear
  B)
             Avoid the production of eddy currents done clear
  C)
             Increase the production of eddy currents done clear
  D)
             Increase the production of induced e.m.f. done clear
  View Solution play_arrow

• question_answer89)
  Two thin, long, parallel wires, separated by a distance ?d? carry a current of ?i? A in the same direction. They will [AIEEE 2005]
  A)
             Attract each other with a force of \[{{\mu }_{0}}{{i}^{2}}/(2\pi {{d}^{2}})\] done clear
  B)
             Repel each other with a force of \[{{\mu }_{0}}{{i}^{2}}/(2\pi {{d}^{2}})\] done clear
  C)
             Attract each other with a force of \[{{\mu }_{0}}{{i}^{2}}/(2\pi d)\] done clear
  D)
              Repel each other with a force of \[{{\mu }_{0}}{{i}^{2}}/(2\pi d)\] done clear
  View Solution play_arrow

• question_answer90)
  Three long, straight parallel wires carrying current, are arranged as shown in figure. The force experienced by a 25 cm length of wire C is                                                           [KCET 2005]
  A)
             10-3 N                                       done clear
  B)
             2.5 ´ 10-3 N done clear
  C)
             Zero                                          done clear
  D)
             1.5 ´ 10-3 N done clear
  View Solution play_arrow

• question_answer91)
  A circular coil of 20 turns and radius 10 cm is placed in uniform magnetic field of 0.10 T normal to the plane of the coil. If the current in coil is 5 A, then the torque acting on the coil will be                                         [J & K CET 2005]
  A)
             31.4 Nm                                  done clear
  B)
             3.14 Nm done clear
  C)
             0.314 Nm                                done clear
  D)
             Zero done clear
  View Solution play_arrow