# Solved papers for NEET Physics Magnetic Effects of Current / करंट का चुंबकीय प्रभाव NEET PYQ-Magnetic Effects Of Current

### done NEET PYQ-Magnetic Effects Of Current Total Questions - 55

• question_answer1) 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 induction at their centres will be:              [AIPMT 1998]

A)
2 : 1

B)
1 : 4

C)
4 : 1

D)
1 : 2

• question_answer2) Two long parallel wires are at a distance of 1 m. Both of them carry one ampere of current. The force of attraction per unit length between the two wires is:                                                                                       [AIPMT 1998]

A)
$2\times {{10}^{-7}}\,N/m$

B)
$2\times {{10}^{-8}}\,N/m$

C)
$5\times {{10}^{-8}}\,N/m$

D)
${{10}^{-7}}\,N/m$

• question_answer3) If a long hollow copper pipe carries a current, then magnetic field is produced:         [AIPMT 1999]

A)
inside the pipe only

B)
outside the pipe only

C)
both inside and outside the pipe

D)
no where

• question_answer4) A straight wire of diameter 0.5 mm carrying a current of 1A is replaced by another wire of diameter 1 mm carrying the same current. The strength of magnetic field far away is:                                                                          [AIPMT 1999]

A)
twice the earlier value

B)
one-half of the earlier value

C)
one quarter of the earlier value

D)
same as earlier value

• question_answer5) 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:                                                                                                                                       [AIPMT 1999]

A)
$0.2\text{ }T$

B)
$2\times {{10}^{-4}}T~$

C)
$6.28\times {{10}^{-4}}T$

D)
$9.8\times {{10}^{-4}}T$

• question_answer6) An electron moves with a velocity $1\times {{10}^{3}}\,m/s$ in a magnetic field of induction $0.3\text{ }T$ at an angle ${{30}^{o}}$. If $\frac{e}{m}$ of electron is $1.76\times {{10}^{11}}\,C/kg$ the radius of the path is nearly:        [AIPMT 2000]

A)
${{10}^{-8}}\,m$

B)
$2\times {{10}^{-8}}\,m$

C)
${{10}^{-6}}\,m$

D)
${{10}^{-10}}\,m$

• question_answer7) Current is flowing in a coil of area A and number of turns N, then magnetic moment of the coil M is equal to: [AIPMT 2001]

A)
$NiA$

B)
$\frac{Ni}{A}$

C)
$\frac{Ni}{\sqrt{A}}$

D)
${{N}^{2}}Ai$

• question_answer8) In a certain region of space electric field $\vec{E}$ and magnetic field $\vec{B}$ are perpendicular to each other and an electron enters in region perpendicular to the direction of $\vec{B}$ and $\vec{E}$ both and moves undeflected, then velocity of electron is:                                                                                                         [AIPMT 2001]

A)
$\frac{|\vec{E}|}{|\vec{B}|}$

B)
$\vec{E}\times \vec{B}$

C)
$\frac{|\vec{B}|}{|\vec{E}|}$

D)
$\vec{E}.\vec{B}$

• question_answer9) A charged particle of charge q and mass m enters perpendicularly in a magnetic field $\vec{B}$. Kinetic energy of the particle is E; then frequency of rotation is:                                                                                       [AIPMT 2001]

A)
$\frac{qB}{m\pi }$

B)
$\frac{qB}{2\pi m}$

C)
$\frac{qBM}{2\pi m}$

D)
$\frac{qB}{2\pi E}$

• question_answer10) The magnetic field of a given length of wire carrying a current for a single turn circular coil at centre is B, then its value for two turns for the same wire when same current passing through it is:                                          [AIPMT 2002]

A)
$\frac{B}{4}$

B)
$\frac{B}{2}$

C)
$2\,B$

D)
$4\,B$

• question_answer11) A charge q moves in a region where electric field  $\vec{E}$ and magnetic field $\vec{B}$ both exist, then the force on it is:                                                                                                                       [AIPMT 2002]

A)
$q\,\vec{v}\,\times \,\vec{B}$

B)
$q\,\vec{E}+q\,\vec{v}\,\times \,\vec{B}$

C)
$q\,\vec{B}+q\,\vec{B}\,\times \,\vec{v}$

D)
$q\,\vec{B}+q\,(\vec{E}\times \vec{v})$

• question_answer12) A charged particle moves through a magnetic field in a direction perpendicular to it.                             [AIPMT 2003]

A)
acceleration remains unchanged

B)
velocity remains unchanged

C)
speed of the particle remains unchanged

D)
direction of the particle remains unchanged

• question_answer13) A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of rums per cm is halved, the new value of the magnetic field is                                            [AIPMT 2003]

A)
2B

B)
4B

C)
$B/2$

D)
B

• question_answer14) A coil in the shape of an equilateral triangle of side (is suspended between the pole pieces of a permanent magnet such that $\vec{B}$ is in plane of the coil. If due to a current i in the triangle a torque t acts on it, the side 2 of the triangle is:                                                                                [AIPMT (S) 2005]

A)
$\frac{2}{\sqrt{3}}{{\left( \frac{\tau }{Bi} \right)}^{1/2}}$

B)
$\frac{2}{\sqrt{3}}\left( \frac{\tau }{Bi} \right)$

C)
$2{{\left( \frac{\tau }{\sqrt{3}\,Bi} \right)}^{1/2}}$

D)
$\frac{1}{\sqrt{3}}\,\frac{\tau }{Bi}$

• question_answer15)  A very long straight wire carries a current I. At the instant when a charge $+\text{ }Q$ at point P has velocity $\vec{v},$ as shown, the force on the charge is : [AIPMT (S) 2005]

A)
opposite to ox

B)
along ox

C)
opposite to oy

D)
along oy

• question_answer16) An electron moves in a circular orbit with a uniform speed v. It produces a magnetic field B, at the centre of the circle. The radius of the circle is proportional to:                                                                                    [AIPMT (S) 2005]

A)
$\frac{B}{v}$

B)
$\frac{v}{B}$

C)
$\sqrt{\frac{v}{B}}$

D)
$\sqrt{\frac{B}{v}}$

• question_answer17) 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:                                                                             [AIPMT (S) 2006]

A)
angle between $\vec{v}$ and $\vec{B}$ is necessarily ${{90}^{o}}$

B)
angle between $\vec{v}$ and $\vec{B}$ can have any value other than ${{90}^{o}}$

C)
angle between $\vec{v}$ and $\vec{B}$ can have any value other than zero and ${{180}^{o}}$

D)
angle between $\vec{v}$ and $\vec{B}$ is either zero or ${{180}^{o}}$

• question_answer18) Two circular coils 1 and 2 are made from the same wire but the radius of the 1st coil is twice that of die 2nd coil. What is the ratio of potential difference applied across them so that die magnetic field at their centres is the same?                                                                                                                         [AIPMT (S) 2006]

A)
3

B)
4

C)
6

D)
2

• question_answer19) Under the influence of a uniform magnetic field a charged particle is moving in a circle of radius R with constant speed v. The time period of the motion:                                                                                         [AIPMT (S) 2007]

A)
depends on v and not on R

B)
depends on both R and v

C)
is independent of both R and v

D)
depends on R and not on v

• question_answer20) A charged particle (charge q) is moving in a circle of radius R with uniform speed v. The associated magnetic moment u is given by:                                                                                                                    [AIPMT (S) 2007]

A)
$\frac{qvR}{2}$

B)
$qv{{R}^{2}}$

C)
$\frac{qv{{R}^{2}}}{2}$

D)
$qvR$

• question_answer21) In a mass spectrometer used for measuring the masses of ions, the ions are initially accelerated by an electric potential V and then made to describe semicircular paths of radius R using a magnetic field B. If V and B are kept constant, the ratio $\left( \frac{\text{charge}\,\text{on}\,\text{the}\,\text{ion}}{\text{mass}\,\text{of}\,\text{the}\,\text{ion}} \right)$ will be proportional to:                                                                                                   [AIPMT (S) 2007]

A)
$\frac{1}{R}$

B)
$\frac{1}{{{R}^{2}}}$

C)
${{R}^{2}}$

D)
R

• question_answer22) A beam of electrons passes undetected through mutually perpendicular electric and magnetic fields. If the electric field is switched off, and the same magnetic field is maintained, the electrons move:     [AIPMT (S) 2007]

A)
in an elliptical orbit

B)
in a circular orbit

C)
along a parabolic path

D)
along a straight line

• question_answer23) A particle mass m, charge Q and kinetic energy T enters a transverse uniform magnetic field of induction $\overrightarrow{B}$. After 3s the kinetic energy of the particle will be                   [AIPMPT (S) 2008]

A)
3T

B)
2T

C)
T

D)
AT

• question_answer24)  A thin conducting ring of radius R is given a charge $+Q$. The electric field at the centre O of the ring due to the charge on the part AKB of the ring is E. The electric field at the centre due to the charge on the part ACDB of the ring is          [AIPMPT (S) 2008]

A)
3E along KO

B)
E along OK

C)
E along KO

D)
3E along OK

• question_answer25) A circular disc of radius 0.2 m is placed in a uniform magnetic field of induction $\frac{1}{\pi }\left( \frac{Wb}{{{m}^{2}}} \right)$ in such a way that its axis makes an angle of ${{60}^{o}}$ with $\overrightarrow{B}$. The magnetic flux linked with the disc is                                                                                                           [AIPMPT (S) 2008]

A)
0.02 Wb

B)
0.06 Wb

C)
0.08 Wb

D)
0.01 Wb

• question_answer26) 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                                                                                        [AIPMT (S) 2009]

A)
depends on v arid not on R

B)
depends on R and not on v

C)
is independent of both v and R

D)
depends on both v and R

• question_answer27) A rectangular, a square, a circular and an elliptical loop, all in the $(x,\,y)$ plane, are moving out of a uniform magnetic field with a constant velocity, $\vec{v}=v\hat{i}$. The magnetic field is directed along the negative z-axis direction. The induced emf, during the passage of these loops, out of the field region, will not remain constant for        [AIPMT (S) 2009]

A)
the rectangular, circular and elliptical loops

B)
the circular and the elliptical loops

C)
only the elliptical loop

D)
any of the four loops

• question_answer28) The magnetic force acting on a charged particle of charge $-\,2\mu C$ in a magnetic field of 2T acting in y direction, when the particle velocity is $(2\hat{j}+3\hat{j})\times {{10}^{6}}\,m{{s}^{-1}}$ is          [AIPMT (S) 2009]

A)
8 N in  z direction

B)
4 N in z direction

C)
8 N in y direction

D)
8 N in z direction

• question_answer29) A beam of cathode rays is subjected to crossed Electric (X) and Magnetic fields . The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by (where V is the potential difference between cathod and anode)             [AIPMT (S) 2010]

A)
$\frac{{{B}^{2}}}{2V{{E}^{2}}}$

B)
$\frac{2V{{B}^{2}}}{{{E}^{2}}}$

C)
$\frac{2V{{E}^{2}}}{{{B}^{2}}}$

D)
$\frac{{{E}^{2}}}{2V{{B}^{2}}}$

• question_answer30) 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                [AIPMT (M) 2010]

A)
$\frac{{{\mu }_{0}}i}{2\sqrt{2}R}$

B)
$\frac{{{\mu }_{0}}i}{2R}$

C)
$\frac{{{\mu }_{0}}i}{4R}$

D)
$\frac{{{\mu }_{0}}i}{\sqrt{2}R}$

• question_answer31) A closely wound solenoid of 2000 turns and area of cross-section $1.5\times {{10}^{-4}}{{m}^{2}}$ 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 $5\times {{10}^{-2}}T$ making an angle of 30° with the axis of the solenoid. The torque on the solenoid will be                                                                                                       [AIPMT (M) 2010]

A)
$3\times {{10}^{-3}}N-m$

B)
$1.5\times {{10}^{-3}}N-m$

C)
$1.5\times {{10}^{-2}}N-m$

D)
$3\times {{10}^{-2}}N-m$

• question_answer32) A particle having a mass of ${{10}^{-2}}\,kg$ carries a charge of $5\times {{10}^{-8}}C$. The particle is given an initial horizontal velocity of ${{10}^{5}}m{{s}^{-1}}$ in the presence of electric field $\overset{\to }{\mathop{\mathbf{E}}}\,$ and magnetic field    $\overset{\to }{\mathop{\mathbf{B}}}\,$ . To keep the particle moving in a horizontal direction, it is necessary that (1)  $\overset{\to }{\mathop{\mathbf{B}}}\,$ should be perpendicular to the direction of velocity and $\overset{\to }{\mathop{\mathbf{E}}}\,$ should be along the direction of velocity. (2) Both $\overset{\to }{\mathop{\mathbf{B}}}\,$ and $\overset{\to }{\mathop{\mathbf{E}}}\,$ should be along the direction of velocity. (3) Both $\overset{\to }{\mathop{\mathbf{B}}}\,$ and $\overset{\to }{\mathop{\mathbf{E}}}\,$ are mutually perpendicular and perpendicular to the direction of velocity. (4) $\overset{\to }{\mathop{\mathbf{B}}}\,$ should be along the direction of velocity and $\overset{\to }{\mathop{\mathbf{E}}}\,$ should be perpendicular to the direction of velocity. Which one of the following pairs of statements is possible?                               [AIPMT (M) 2010]

A)
(1) and (3)

B)
(3) and (4)

C)
(2) and (3)

D)
(2) and (4)

• question_answer33)  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 [AIPMT (M) 2011]

A)
a net repulsive force away from the conductor

B)
a net torque acting upward perpendicular to the horizontal plane

C)
a net torque acting downward normal to the horizontal plane

D)
a net attractive force towards the conductor

• question_answer34) 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 centre of the ring is                                                  [AIPMT (M) 2011]

A)
$\frac{{{\mu }_{0}}qf}{2R}$

B)
$\frac{{{\mu }_{0}}q}{2f\,R}$

C)
$\frac{{{\mu }_{0}}q}{2\pi f\,R}$

D)
$\frac{{{\mu }_{0}}qf}{2\pi R}$

• question_answer35) The electric and the magnetic field, associated with an electromagnetic wave, propagating along the +z-axis, can be represented by         [AIPMT (S) 2011]

A)
$[\mathbf{E}={{E}_{0}}\mathbf{\hat{k}},\mathbf{B}={{B}_{0}}\mathbf{\hat{i}}]$

B)
$[\mathbf{E}={{E}_{0}}\mathbf{\hat{j}}\,,\mathbf{B}={{B}_{0}}\mathbf{\hat{j}}\,]$

C)
$[\mathbf{E}={{E}_{0}}\mathbf{\hat{j}}\,,\mathbf{B}={{B}_{0}}\mathbf{\hat{k}}\,]$

D)
$[\mathbf{E}={{E}_{0}}\mathbf{\hat{i}}\,,\mathbf{B}={{B}_{0}}\mathbf{\hat{j}}\,]$

• question_answer36)  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              [AIPMT (S) 2011]

A)
$-\mathbf{F}$

B)
$\mathbf{F}$

C)
$\sqrt{2}\mathbf{F}$

D)
$-\sqrt{2}\mathbf{F}$

• question_answer37) 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 $\alpha -$article to describe a circle of same radius in the same field?                              [AIPMT (M) 2012]

A)
2 MeV

B)
1 MeV

C)
0.5 MeV

D)
4 MeV

• question_answer38) 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 $2\,I,$ respectively. The resultant magnetic field induction at the centre will be          [AIPMT (S) 2012]

A)
$\frac{\sqrt{5}{{\mu }_{0}}I}{2R}$

B)
$\frac{3{{\mu }_{0}}I}{2R}$

C)
$\frac{{{\mu }_{0}}I}{2R}$

D)
$\frac{{{\mu }_{0}}I}{R}$

• question_answer39) 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  used in the cyclotron and the kinetic energy (1C) of the proton beam, produced by it, are given by                                                                                 [AIPMT (S) 2012]

A)
$B=\frac{mv}{e}$ and $K=2m{{\pi }^{2}}{{v}^{2}}{{R}^{2}}$

B)
$B=\frac{2\pi mv}{e}$ and $K={{m}^{2}}\pi v{{R}^{2}}$

C)
$B=\frac{2\pi mv}{e}$ and $K=2m{{\pi }^{2}}{{v}^{2}}{{R}^{2}}$

D)
$B=\frac{mv}{e}$ and $K={{m}^{2}}\pi v{{R}^{2}}$

• question_answer40) 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 ${{\upsilon }_{0}}$ it moves with an initial acceleration $3{{a}_{0}}$ towards west. The electric and magnetic fields in the room are                                                                                   [NEET 2013]

A)
$\frac{m{{a}_{0}}}{e}\text{west},\frac{2m{{a}_{0}}}{e{{v}_{0}}}\text{up}$

B)
$\frac{m{{a}_{0}}}{e}\text{west},\frac{2m{{a}_{0}}}{e{{v}_{0}}}\text{dwon}$

C)
$\frac{m{{a}_{0}}}{e}\text{east},\frac{3m{{a}_{0}}}{e{{v}_{0}}}\text{up}$

D)
$\frac{m{{a}_{0}}}{e}\text{west},\frac{3m{{a}_{0}}}{e{{v}_{0}}}\text{down}$

• question_answer41) A current loop in a magnetic field                                                                          [NEET2013]

A)
experiences a torque whether the field is uniform or non-uniform in all orientations

B)
can be in equilibrium in one orientations

C)
can be equilibrium in two orientations, both the equilibrium states are unstable

D)
can be in equilibrium in two orientations, one stable while the other is unstable

• question_answer42) 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                                                                                                                     [NEET 2014]

A)
$\frac{{{\mu }_{0}}}{2\pi d}\left( \frac{{{l}_{1}}}{{{l}_{2}}} \right)$

B)
$\frac{{{\mu }_{0}}}{2\pi d}({{l}_{1}}+{{l}_{2}})$

C)
$\frac{{{\mu }_{0}}}{2\pi d}(l_{1}^{2}+l_{2}^{2})$

D)
$\frac{{{\mu }_{0}}}{2\pi d}{{(l_{1}^{2}+l_{2}^{2})}^{1/2}}$

• question_answer43)  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 B. is lying in YZ plane. Magnetic field at point O is [NEET  2015]

A)
$\mathbf{B}=\frac{{{\mu }_{0}}}{4\pi }\frac{l}{R}(\pi \hat{i}+2\hat{k})$

B)
$\mathbf{B}=-\frac{{{\mu }_{0}}}{4\pi }\frac{l}{R}(\pi \hat{i}-2\hat{k})$

C)
$\mathbf{B}=-\frac{{{\mu }_{0}}}{4\pi }\frac{l}{R}(\pi \hat{i}+2\hat{k})$

D)
$\mathbf{B}=\frac{{{\mu }_{0}}}{4\pi }\frac{l}{R}(\pi \hat{i}-2\hat{k})$

• question_answer44) An electron moving in a circular orbit of radius r makes n rotations per second. The magnetic field produced at the centre has magnitude                                                                                                          [NEET  2015]

A)
$\frac{{{\mu }_{0}}ne}{2\pi r}$

B)
zero

C)
$\frac{{{\mu }_{0}}{{n}^{2}}e}{r}$

D)
$\frac{{{\mu }_{0}}ne}{2r}$

• question_answer45) 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                                                                                            [NEET (Re) 2015]

A)
4 MeV

B)
0.5 MeV

C)
1.5 MeV

D)
1 MeV

• question_answer46) A rectangular coil of length 0.12 m and width 0.1 m having 50 turns of wire is suspended vertically in a uniform magnetic field of strength $0.2\,\,Wb/{{m}^{2}}$ . The coil carries a current of 2 A. If the plane of the coil is inclined at an angle of ${{30}^{o}}$ with the direction of the field, the torque required to keep the coil in stable equilibrium will be [NEET (Re) 2015]

A)
0.15 Nm

B)
0.20 Nm

C)
0.24 Nm

D)
0.12 Nm

• question_answer47)  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 :-                                                                      [NEET - 2016]

A)
$\frac{2{{\mu }_{0}}li}{3\pi }$

B)
$\frac{{{\mu }_{0}}li}{2\pi }$

C)
$\frac{2{{\mu }_{0}}liL}{3\pi }$

D)
$\frac{{{\mu }_{0}}liL}{2\pi }$

• question_answer48) A long straight wire of radius a 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 distances $\frac{a}{2}$ and 2a respectively, from the axis of the wire is :                                                                                                                                            [NEET - 2016]

A)
$\frac{1}{4}$

B)
$\frac{1}{2}$

C)
1

D)
4

• question_answer49)  An arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current $'I'$ along the same direction is shown in Fig. Magnitude of force per unit length on the middle wire $'B'$ is given by [NEET-2017]

A)
$\frac{{{\mu }_{0}}{{l}^{2}}}{\sqrt{2}\pi d}$

B)
$\frac{{{\mu }_{0}}{{l}^{2}}}{2\pi d}$

C)
$\frac{2{{\mu }_{0}}{{l}^{2}}}{\pi d}$

D)
$\frac{\sqrt{2}{{\mu }_{0}}{{l}^{2}}}{\pi d}$

• question_answer50)   A 250-Turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of $85\,\mu A$ and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by ${{180}^{o}}$ against the torque is         [NEET-2017]

A)
$1.15\,\mu J$

B)
$9.1\,\mu J$

C)
$4.55\,\mu J$

D)
$2.3\,\mu J$

• question_answer51) A metallic rod of mass per unit length $0.5\text{ }kg\text{ }{{m}^{1}}$ is lying horizontally on a smooth inclined plane which makes an angle of $30{}^\circ$ 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                                                                                                          [NEET - 2018]

A)
$\text{14}\text{.76 A}$

B)
$\text{5}\text{.98 A}$

C)
$\text{7}\text{.14 A}$

D)
$\text{11}\text{.32 A}$

• question_answer52) 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                                                    [NEET - 2018]

A)
$250\,\,\Omega$

B)
$25\,\,\Omega$

C)
$40\,\,\Omega$

D)
$500\,\,\Omega$

• question_answer53) 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:                           [NEET 2019]

A)
4 : 1

B)
1 : 4

C)
2 : 1

D)
1 : 2

• question_answer54) A cylindrical conductor of radius R is carrying a constant current. The plot of the magnitude of the magnetic field, B with the distance, d, from the centre of the conductor, is correctly represented by the figure:                               [NEET 2019]

A)

B)

C)

D)

• question_answer55) 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:                                                                                                            [NEET 2020] $\left( {{\mu }_{0}}=4\pi \times {{10}^{-7}}T\,m\,{{A}^{-1}} \right)$

A)
$3.14\times {{10}^{-4}}T$

B)
$6.28\times {{10}^{-5}}T$

C)
$3.14\times {{10}^{-5}}T$

D)
$6.28\times {{10}^{-4}}T$