Question 1: Palette 1/80

NEET 2026 MCQ

A 100-turn closely wound circular coil of radius 5 cm has a magnetic field of $3.14 \times 10^{-3} \mathrm{~T}$ at its centre. The current flowing through the coil, and the magnitude of the magnetic moment of this coil are, respectively :

(Take $\mu_0=4 \pi \times 10^{-7} \mathrm{~T} \mathrm{~m} / \mathrm{A}$ )

A

$2 \mathrm{~A}, 10 \mathrm{~A} \mathrm{~m}^2$

B

$2.5 \mathrm{~A}, 20 \mathrm{~A} \mathrm{~m}^2$

C

$2 \mathrm{~A}, 4 \mathrm{~A} \mathrm{~m}^2$

D

$2.5 \mathrm{~A}, 2 \mathrm{~A} \mathrm{~m}^2$

Question 2: Palette 2/80

NEET 2026 MCQ

The figure given below shows a long straight solid wire of circular cross-section of radius ' $a$ ' carrying steady current $I$. The current $I$ is uniformly distributed across its cross-section. The plot which correctly represents the variation of magnetic field $(B)$ with distance $(r)$ from the axis of the conductor in the region is :

A

B

C

D

Question 3: Palette 3/80

NEET 2026 MCQ

A current $l_0$ flows through a metallic circular loop of radius $r$ as shown in the figure. Resistance of the segment $A B C$ is half that of $A D C$. Magnitude of magnetic field at the centre $O$ of the loop is :

A

$\frac{\mu_0 I_0}{2 \pi r}$

B

$\frac{\mu_0 I_0}{12 r}$

C

$\frac{\mu_0 I_0}{4 r}$

D

$\frac{\mu_0 I_0}{2 r}$

Question 4: Palette 4/80

NEET 2026 MCQ

Two infinitely long parallel conducting wires $A$ and $B$ carry currents $I$ and $2 I$, respectively, in the same direction. The wire $A$ has uniform mass per unit length $\lambda$ and lies on an insulated floor. The wire $B$ is kept fixed at a height $h$ above the floor. The minimum magnitude of $h$ so that the wire $A$ does not rise from the floor is: [ $g$ is the acceleration due to gravity and $\mu_0$ is the permeability of free space.]

A

$\frac{4 \mu_0 I^2}{\pi \lambda g}$

B

$\frac{\mu_0 I^2}{2 \pi \lambda g}$

C

$\frac{\mu_0 I^2}{\pi \lambda g}$

D

$\frac{2 \mu_0 I^2}{\pi \lambda g}$

Question 5: Palette 5/80

NEET 2025 MCQ

A parallel plate capacitor made of circular plates is being charged such that the surface charge density on its plates is increasing at a constant rate with time. The magnetic field arising due to displacement current is:

A

Non-zero everywhere with maximum at the imaginary cylindrical surface connecting peripheries of the plates

B

Zero between the plates and non-zero outside

C

Zero at all places

D

Constant between the plates and zero outside the plates

Question 6: Palette 6/80

NEET 2025 MCQ

A model for quantized motion of an electron in a uniform magnetic field $B$ states that the flux passing through the orbit of the electron in $n(h l e)$ where $n$ is an integer, $h$ is Planck's constant and $e$ is the magnitude of electron's charge. According to the model, the magnetic moment of an electron in its lowest energy state will be ( $m$ is the mass of the electron)

A

$\frac{h e B}{\pi m}$

B

$\frac{h e B}{2 \pi m}$

C

$\frac{h e}{\pi m}$

D

$\frac{h e}{2 \pi m}$

Question 7: Palette 7/80

NEET 2025 MCQ

An electron (mass $9 \times 10^{-31} \mathrm{~kg}$ and charge $1.6 \times 10^{-19} \mathrm{C}$ ) moving with speed $c / 100(c=$ speed of light) is injected into a magnetic field $\vec{B}$ of magnitude $9 \times 10^{-4} \mathrm{~T}$ perpendicular to its direction of motion. We wish to apply an uniform electric field $\vec{E}$ together with the magnetic field so that the electron does not deflect from its path. Then (speed of light $c=3$ $\times 10^3 \mathrm{~ms}^{-1}$)

A

$\vec{E}$ is parallel to $\vec{B}$ and its magnitude is $27 \times 10^2 \mathrm{~V} \mathrm{~m}^{-1}$

B

$\vec{E}$ is parallel to $\vec{B}$ and its magnitude is $27 \times 10^4 \mathrm{~V} \mathrm{~m}^{-1}$

C

$\vec{E}$ is perpendicular to $\vec{B}$ and its magnitude is $27 \times 10^4 \mathrm{~V} \mathrm{~m}^{-1}$

D

$\vec{E}$ is perpendicular to $\vec{B}$ and its magnitude is $27 \times 10^2 \mathrm{~V} \mathrm{~m}^{-1}$

Question 8: Palette 8/80

NEET 2025 MCQ

A 2 amp current is flowing through two different small circular copper coils having radii ratio $1: 2$. The ratio of their respective magnetic moments will be

A

$2: 1$

B

$4: 1$

C

$1: 4$

D

$1: 2$

Question 9: Palette 9/80

NEET 2024 MCQ

A tightly wound 100 turns coil of radius $10 \mathrm{~cm}$ carries a current of $7 \mathrm{~A}$. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as $4 \pi \times 10^{-7} \mathrm{SI}$ units):

A

44 mT

B

4.4 T

C

4.4 mT

D

44 T

Question 10: Palette 10/80

NEET 2024 MCQ

A parallel plate capacitor is charged by connecting it to a battery through a resistor. If $I$ is the current in the circuit, then in the gap between the plates:

A

There is no current

B

Displacement current of magnitude equal to $I$ flows in the same direction as $I$

C

Displacement current of magnitude equal to $I$ flows in a direction opposite to that of $I$

D

Displacement current of magnitude greater than $I$ flows but can be in any direction

Question 11: Palette 11/80

NEET 2023 MCQ

A long straight wire of length $2 \mathrm{~m}$ and mass $250 \mathrm{~g}$ is suspended horizontally in a uniform horizontal magnetic field of $0.7 \mathrm{~T}$. The amount of current flowing through the wire will be $\left(\mathrm{g}=9.8 \mathrm{~ms}^{-2}\right)$ :

A

2.45 A

B

2.25 A

C

2.75 A

D

1.75 A

Question 12: Palette 12/80

NEET 2023 MCQ

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:

A

will turn towards right of direction of motion

B

will turn towards left of direction of motion

C

speed will decrease

D

speed will increase

Question 13: Palette 13/80

NEET 2023 MCQ

A wire carrying a current $I$ along the positive $\mathrm{x}$-axis has length $L$. It is kept in a magnetic field $\overrightarrow{\mathrm{B}}=(2 \hat{\mathrm{i}}+3 \hat{\mathrm{j}}-4 \hat{\mathrm{k}}) \mathrm{T}$. The magnitude of the magnetic force acting on the wire is :

A

$\sqrt{5} \mathrm{~IL}$

B

$5 \mathrm{~IL}$

C

$\sqrt{3}$ IL

D

3 IL

Question 14: Palette 14/80

NEET 2023 MCQ

A very long conducting wire is bent in a semi-circular shape from $A$ to $B$ as shown in figure. The magnetic field at point $P$ for steady current configuration is given by :

A

$\frac{\mu_{0} \mathrm{i}}{4 \mathrm{R}}$ pointed away from the page

B

$\frac{\mu_{0} \mathrm{i}}{4 \mathrm{R}}\left[1-\frac{2}{\pi}\right]$ pointed away from page

C

$\frac{\mu_{0} \mathrm{i}}{4 \mathrm{R}}\left[1-\frac{2}{\pi}\right]$ pointed into the page

D

$\frac{\mu_{0} \mathrm{i}}{4 \mathrm{R}}$ pointed into the page

Question 15: Palette 15/80

NEET 2022 MCQ

A closely packed coil having 1000 turns has an average radius of 62.8 cm. If current carried by the wire of the coil is 1 A, the value of magnetic field produced at the centre of the coil will be (permeability of free space $ = 4\pi \times {10^{ - 7}}$ H/m) nearly

A

10^$-$3 T

B

10^$-$1 T

C

10^$-$2 T

D

10² T

Question 16: Palette 16/80

NEET 2022 MCQ

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

Question 17: Palette 17/80

NEET 2022 MCQ

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$\pi$ $\times$ 10^$-$7 SI unit)

A

1 $\times$ 10^$-$4 Nm^$-$1 and is repulsive

B

2 $\times$ 10^$-$4 Nm^$-$1 and is attractive

C

2 $\times$ 10^$-$4 Nm^$-$1 and is repulsive

D

1 $\times$ 10^$-$4 Nm^$-$1 and is attractive

Question 18: Palette 18/80

NEET 2022 MCQ

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

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

B

$3.14 \times {10^{ - 7}}$ T

C

$6.28 \times {10^{ - 7}}$ T

D

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

Question 19: Palette 19/80

NEET 2022 MCQ

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 $\times$ 10^$-$2 T

B

12.56 $\times$ 10^$-$2 T

C

12.56 $\times$ 10^$-$4 T

D

6.28 $\times$ 10^$-$4 T

Question 20: Palette 20/80

NEET 2022 MCQ

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

Question 21: Palette 21/80

NEET 2022 MCQ

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 ${1 \over r}$ dependence for the outside region.

D

A linearly decreasing function of distance upto the boundary of the wire and then a linearly increasing one of the outside region.

Question 22: Palette 22/80

NEET 2021 MCQ

A thick current carrying cable of radius 'R' carries current 'I' uniformly distributed across its cross section. The variation of magnetic field B(r) due to the cable with the distance 'r' from the axis of the cable is represented by :

A

B

C

D

Question 23: Palette 23/80

NEET 2021 MCQ

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 $\times$ 10^$-$20 N

B

4 $\times$ 10^$-$20 N

C

8$\pi$ $\times$ 10^$-$20 N

D

4$\pi$ $\times$ 10^$-$20 N

Question 24: Palette 24/80

NEET 2020 MCQ

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 :
$\left( {{\mu _0} = 4\pi \times {{10}^{ - 7}}Tm{{A}^{-1}}} \right)$

A

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

B

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

C

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

D

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

Question 25: Palette 25/80

NEET 2019 MCQ

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

Question 26: Palette 26/80

NEET 2019 MCQ

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

Question 27: Palette 27/80

NEET 2018 MCQ

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

7.14 A

B

5.98 A

C

14.76 A

D

11.32 A

Question 28: Palette 28/80

NEET 2018 MCQ

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 $

Question 29: Palette 29/80

NEET 2017 MCQ

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

${{2{\mu _0}{I^2}} \over {\pi d}}$

B

${{\sqrt 2 {\mu _0}{I^2}} \over {\pi d}}$

C

${{{\mu _0}{I^2}} \over {\sqrt 2 \pi d}}$

D

${{{\mu _0}{I^2}} \over {2\pi d}}$

Question 30: Palette 30/80

NEET 2016 MCQ

An electron is moving in a circular path under the influence of a transverse magnetic field of 3.57 $ \times $ 10^-2 T. If the value of e/m is 1.76 $ \times $ 10¹¹ C kg^$-$1, the frequency of revoluation of the electron is

A

1 GHz

B

100 MHz

C

62.8 MHz

D

6.28 MHz

Question 31: Palette 31/80

NEET 2016 MCQ

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

n²B

C

2nB

D

2n²B

Question 32: Palette 32/80

NEET 2016 MCQ

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 distance ${a \over 2}$ and 2$a$ respectively, from the axis of the wire is

A

1

B

4

C

${1 \over 4}$

D

${1 \over 2}$

Question 33: Palette 33/80

NEET 2016 MCQ

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

${{2{\mu _0}liL} \over {3\pi }}$

B

${{{\mu _0}liL} \over {2\pi }}$

C

${{2{\mu _0}li} \over {3\pi }}$

D

${{{\mu _0}li} \over {2\pi }}$

Question 34: Palette 34/80

NEET 2015 MCQ

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

1.5 MeV

B

1 MeV

C

4 MeV

D

0.5 MeV

Question 35: Palette 35/80

NEET 2015 MCQ

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

${{{\mu _0}{n^2}e} \over r}$

B

${{{\mu _0}ne} \over {2r}}$

C

${{{\mu _0}ne} \over {2\pi r}}$

D

Zero

Question 36: Palette 36/80

NEET 2015 MCQ

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

${1 \over {{{\left( {2x + a} \right)}^2}}}$

B

${1 \over {\left( {2x - a} \right)\left( {2x + a} \right)}}$

C

${1 \over {{x^2}}}$

D

${1 \over {{{\left( {2x - a} \right)}^2}}}$

Question 37: Palette 37/80

NEET 2015 MCQ

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

$\overrightarrow B = - {{{\mu _0}I} \over {4\pi R}}\left( {\pi \widehat i + 2\widehat k} \right)$

B

$\overrightarrow B = {{{\mu _0}I} \over {4\pi R}}\left( {\pi \widehat i - 2\widehat k} \right)$

C

$\overrightarrow B = {{{\mu _0}I} \over {4\pi R}}\left( {\pi \widehat i + 2\widehat k} \right)$

D

$\overrightarrow B = - {{{\mu _0}I} \over {4\pi R}}\left( {\pi \widehat i - 2\widehat k} \right)$

Question 38: Palette 38/80

NEET 2014 MCQ

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 f from $O$ along a direction perpendicular to the plane containing the wires. The magnetic field at the point $P$ will be

A

${{{\mu _0}} \over {2\pi d}}\left( {{{{I_1}} \over {{I_2}}}} \right)$

B

${{{\mu _0}} \over {2\pi d}}\left( {{I_1} + {I_2}} \right)$

C

${{{\mu _0}} \over {2\pi d}}\left( {I_1^2 - I_2^2} \right)$

D

${{{\mu _0}} \over {2\pi d}}{\left( {I_1^2 + I_2^2} \right)^{1/2}}$

Question 39: Palette 39/80

NEET 2014 MCQ

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

${1 \over {499}}G$

B

${{499} \over {500}}G$

C

${1 \over {500}}G$

D

${{500} \over {499}}G$

Question 40: Palette 40/80

NEET 2013 MCQ

A circular coil ABCD carrying a current 'i' is placed in a uniform magnetic field. If the magnetic force on the segment AB is $\overrightarrow F $, the force on the remaining segment BCDA is

A

$ - \overrightarrow F $

B

$3\overrightarrow F $

C

$-$$3\overrightarrow F $

D

$\overrightarrow F $

Question 41: Palette 41/80

NEET 2013 MCQ

A long straight wire carries a certain current and produces a magnetic field 2 $ \times $ 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 $ \times $ 10^$-$19 C)

A

3.2 N

B

3.2 $ \times $ 10^$-$16 N

C

1.6 $ \times $ 10^$-$16 N

D

zero

Question 42: Palette 42/80

NEET 2013 MCQ

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 3$a$₀ towards west. The an initial accelearation 3a₀ towards west. The an initial acceleration 3$a$₀ toward west. The electric and magnetic fields in the room are

A

${{m{a_0}} \over e}$ east,  ${{3m{a_0}} \over {e{v_0}}}$ up

B

${{m{a_0}} \over e}$ east,  ${{3m{a_0}} \over {e{v_0}}}$ down

C

${{m{a_0}} \over e}$ west,  ${{2m{a_0}} \over {e{v_0}}}$ up

D

${{m{a_0}} \over e}$ west,  ${{2m{a_0}} \over {e{v_0}}}$ down

Question 43: Palette 43/80

NEET 2012 MCQ

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

2 MeV

B

1 MeV

C

0.5 MeV

D

4 MeV

Question 44: Palette 44/80

NEET 2012 MCQ

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

Question 45: Palette 45/80

NEET 2012 MCQ

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

A

${{\sqrt 5 {\mu _0}I} \over {2R}}$

B

${{\sqrt 5 {\mu _0}I} \over R}$

C

${{{\mu _0}I} \over {2R}}$

D

${{{\mu _0}I} \over R}$

Question 46: Palette 46/80

NEET 2012 MCQ

An alternating electric field, of frequency $v$, is applied across the does (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

$B = {{m\upsilon } \over e}$  and  $K = 2m{\pi ^2}{\upsilon ^2}{R^2}$

B

$B = {{2\pi m\upsilon } \over e}$  $K = {m^2}\pi \upsilon {R^2}$

C

$B = {{2\pi m\upsilon } \over e}$  $K = 2m{\pi ^2}{v^2}{R^2}$

D

$B = {{m\upsilon } \over e}$  $K = {m^2}\pi \upsilon {R^2}$

Question 47: Palette 47/80

NEET 2011 MCQ

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

${{{\mu _0}qf} \over {2\pi R}}$

B

${{{\mu _0}qf} \over {2R}}$

C

${{{\mu _0}q} \over {2fR}}$

D

${{{\mu _0}q} \over {2\pi fR}}$

Question 48: Palette 48/80

NEET 2011 MCQ

A square loop, carrying a teady 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

Question 49: Palette 49/80

NEET 2011 MCQ

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

${G \over {(S + G)}}$

B

${{{S^2}} \over {\left( {S + G} \right)}}$

C

$\left( {{{SG} \over {S + G}}} \right)$

D

${{{G^2}} \over {(S + G)}}$

Question 50: Palette 50/80

NEET 2011 MCQ

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

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

Question 51: Palette 51/80

NEET 2011 MCQ

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 $\overrightarrow {F,} $ the force on the arm AC is

A

$ - \sqrt 2 \,\overrightarrow F $

B

$-$ $\,\overrightarrow F $

C

$\,\overrightarrow F $

D

$\sqrt 2 \,\overrightarrow F $

Question 52: Palette 52/80

NEET 2010 MCQ

A closely wound solenoid of 2000 turns and area of cross-section 1.5 $ \times $ 10^$-$4 m² 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 tesla making an angle of 30^o with the axis of the solenoid. The torque on the solenoid will be

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 53: Palette 53/80

NEET 2010 MCQ

A particle having a mass of 10^$-$2 kg carries a charge of 5 $ \times $ 10^$-$8 C. The particle is given an initial horizontal velocity of 10⁵ m s^$-$1 in the presence of electric field $\overrightarrow E $ and magnetic field $\overrightarrow B $. To keep the particle moving in a horizontal direction, it is necessary that
(1)  $\overrightarrow B $ should be perpendicular to the direction of velocity and $\overrightarrow E $ should be along the direction of velocity

(2)  Both $\overrightarrow B $ and $\overrightarrow E $ should be along the direction of velocity

(3)  Both $\overrightarrow B $ and $\overrightarrow E $ are mutually perpendicular and perpendicular to the direction of velocity.

(4)  $\overrightarrow B $ should be along the direction of velocity and $\overrightarrow 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)

Question 54: Palette 54/80

NEET 2010 MCQ

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

${{{\mu _0}i} \over {2\sqrt 2 R}}$

B

${{{\mu _0}i} \over {2R}}$

C

${{{\mu _0}i} \over {4R}}$

D

${{{\mu _0}i} \over {\sqrt 2 R}}$

Question 55: Palette 55/80

NEET 2010 MCQ

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 $

Question 56: Palette 56/80

NEET 2010 MCQ

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

A

$3\overrightarrow F $

B

$-$ $\overrightarrow F $

C

$-$ $3\overrightarrow F $

D

$\overrightarrow F $

Question 57: Palette 57/80

NEET 2010 MCQ

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

${{{\mu _0}qf} \over {2\pi R}}$

B

${{{\mu _0}qf} \over {2R}}$

C

${{{\mu _0}q} \over {2fR}}$

D

${{{\mu _0}q} \over {2\pi fR}}$

Question 58: Palette 58/80

NEET 2010 MCQ

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 $

Question 59: Palette 59/80

NEET 2009 MCQ

The magnetic force acting on a charged particle of charge $-$2 $\mu $C in a magnetic frield of 2 T acting in y direction, when the particle velocity is $\left( {2\widehat i + 3\widehat j} \right) \times {10^6}\,m{s^{ - 1}}$

A

4 N in z direction

B

8 N in y direction

C

8 N in z direction

D

8 N in $-$ z direction

Question 60: Palette 60/80

NEET 2009 MCQ

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 $

Question 61: Palette 61/80

NEET 2009 MCQ

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

Question 62: Palette 62/80

NEET 2008 MCQ

A particle of mass m, charge Q and kinetic energy T enters a transverse uniform magnetic field of induction $\overrightarrow B $. After 3 seconds the kinetic energy of the particle will be

A

T

B

4 T

C

3 T

D

2 T

Question 63: Palette 63/80

NEET 2008 MCQ

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

A

$\sqrt {{{\left( {{F_3} - {F_1}} \right)}^2} - F_2^2} $

B

${F_3} - {F_1} + {F_2}$

C

${F_3} - {F_1} - {F_2}$

D

$\sqrt {{{\left( {{F_3} - {F_1}} \right)}^2} + F_2^2} $

Question 64: Palette 64/80

NEET 2008 MCQ

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 $

Question 65: Palette 65/80

NEET 2007 MCQ

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

Question 66: Palette 66/80

NEET 2007 MCQ

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

2 k$\Omega $

D

20 $\Omega $

Question 67: Palette 67/80

NEET 2006 MCQ

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

Question 68: Palette 68/80

NEET 2006 MCQ

When a charged particle moving with velocity $\overrightarrow v $ is subjected to a magnetic field of induction $\overrightarrow 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.

Question 69: Palette 69/80

NEET 2005 MCQ

A very long straight wire carries a current $I$. At the instant when a charge +Q at point P has velocity $\overrightarrow v $, as shown, the force on the charge is

A

along Oy

B

opposite to Oy

C

along Ox

D

opposite to Ox

Question 70: Palette 70/80

NEET 2005 MCQ

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

$v/B$

Question 71: Palette 71/80

NEET 2004 MCQ

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.

Question 72: Palette 72/80

NEET 2004 MCQ

A galvanometer of 50 ohm resistance has 25 divisions. A current of 4 $ \times $ 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

A

$2500\,\Omega $ as a shunt

B

2450 $\Omega $ as a shunt

C

2550 $\Omega $ in series

D

2450 $\Omega $ in series

Question 73: Palette 73/80

NEET 2003 MCQ

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

Question 74: Palette 74/80

NEET 2003 MCQ

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

D

velocity remains unchanged

Question 75: Palette 75/80

NEET 2002 MCQ

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.

Question 76: Palette 76/80

NEET 2002 MCQ

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

Question 77: Palette 77/80

NEET 2002 MCQ

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

A

$q\left( {\overrightarrow v \times \overrightarrow B } \right)$

B

$q\overrightarrow E + q\left( {\overrightarrow v \times \overrightarrow B } \right)$

C

$q\overrightarrow E + \overrightarrow q \left( {\overrightarrow B \times \overrightarrow v } \right)$

D

$q\overrightarrow B + \overrightarrow q \left( {\overrightarrow E \times \overrightarrow v } \right)$

Question 78: Palette 78/80

NEET 2001 MCQ

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

${n^2}iA$

C

$ni{A^2}$

D

${{ni} \over {\sqrt A }}$

Question 79: Palette 79/80

NEET 2001 MCQ

An electron having mass m and kinetic energy E anter in uniform magnetic field B perpendiculaly, then its frequency will be

A

${{eE} \over {qvB}}$

B

${{2\pi m} \over {eB}}$

C

${{eB} \over {2\pi m}}$

D

${{2m} \over {eBE}}$

Question 80: Palette 80/80

NEET 2000 MCQ

The magnetic field at centre, P will be

A

${{{\mu _0}} \over {4\pi }}$

B

${{{\mu _0}} \over {\pi }}$

C

${{{\mu _0}} \over {2\pi }}$

D

$4{\mu _0}\pi $