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Physics chapters

Moving Charges and Magnetism

20 JEE Main questions · Physics

Sources of magnetic field

  1. PhysicsJEE Main 21 Jan 2026, Shift 2·Q17·MCQ·Moderate
    Open
    An infinitely long straight wire carrying current I is bent in a planar shape as shown in the diagram. The radius of the circular part is r. The magnetic field at the centre O of the circular loop is :
    1. (1)μ02πIr(π+1) i^\dfrac{\mu_0}{2\pi}\dfrac{I}{r}(\pi + 1)\,\hat i
    2. (2)−μ02πIr(π−1) i^-\dfrac{\mu_0}{2\pi}\dfrac{I}{r}(\pi - 1)\,\hat i
    3. (3)μ02πIr(π−1) i^\dfrac{\mu_0}{2\pi}\dfrac{I}{r}(\pi - 1)\,\hat i
    4. (4)−μ02πIr(π+1) i^-\dfrac{\mu_0}{2\pi}\dfrac{I}{r}(\pi + 1)\,\hat i
    We corrected a printing error in the original paper

    Source printed “planer”.

  2. PhysicsJEE Main 23 Jan 2026, Shift 2·Q4·MCQ·Easy–moderate
    Open
    The current passing through a conducting loop in the form of equilateral triangle of side 434\sqrt3 cm is 2 A. The magnetic field at its centroid is α×10−5\alpha\times10^{-5} T. The value of α\alpha is .
    (Given: μo=4π×10−7\mu_o = 4\pi\times10^{-7} SI units)
    1. (1)232\sqrt3
    2. (2)3\sqrt3
    3. (3)333\sqrt3
    4. (4)32\dfrac{\sqrt3}{2}
  3. PhysicsJEE Main 24 Jan 2026, Shift 2·Q7·MCQ·Easy–moderate
    Open
    Two identical circular loops P and Q each of radius rr are lying in parallel planes such that they have common axis. The currents through P and Q are II and 4I4I respectively in clockwise direction as seen from O. The net magnetic field at O is:
    1. (1)3μ0I42 r\dfrac{3\mu_0 I}{4\sqrt2\, r} toward P
    2. (2)μ0I42 r\dfrac{\mu_0 I}{4\sqrt2\, r} toward P
    3. (3)μ0I42 r\dfrac{\mu_0 I}{4\sqrt2\, r} towards Q
    4. (4)3μ0I42 r\dfrac{3\mu_0 I}{4\sqrt2\, r} towards Q
    We corrected a printing error in the original paper

    Source printed “The current through P and Q are”.

  4. PhysicsJEE Main 28 Jan 2026, Shift 1·Q18·MCQ·Easy–moderate
    Open
    The magnetic field at the centre of a current carrying circular loop of radius RR is 16 μ16\ \muT. The magnetic field at a distance x=3Rx = \sqrt3 R on its axis from the centre is μ\muT.
    1. (1)222\sqrt2
    2. (2)4
    3. (3)2
    4. (4)8
  5. PhysicsJEE Main 28 Jan 2026, Shift 2·Q14·MCQ·Easy–moderate
    Open
    A long cylindrical conductor with large cross section carries an electric current distributed uniformly over its cross-section. Magnetic field due to this current is:
    A.maximum at either ends of the conductor and minimum at the midpoint
    B.maximum at the axis of the conductor
    C.minimum at the surface of the conductor
    D.minimum at the axis of the conductor
    E.same at all points in the cross-section of the conductor
    Choose the correct answer from the options given below:
    1. (1)D Only
    2. (2)A, D Only
    3. (3)B, C Only
    4. (4)E Only
  6. PhysicsJEE Main 2 Apr 2026, Shift 1·Q14·MCQ·Moderate
    Open
    Two identical long current carrying wires are bent into the shapes shown in the following figures. If the magnitude of magnetic fields at the centres P and Q of a semicircular arc are B1B_1 and B2B_2 respectively, then the ratio B1B2\dfrac{B_1}{B_2} is .
    1. (1)2+π1+π\dfrac{2+\pi}{1+\pi}
    2. (2)1+π1−π\dfrac{1+\pi}{1-\pi}
    3. (3)2+π1−π\dfrac{2+\pi}{1-\pi}
    4. (4)1+π2−π\dfrac{1+\pi}{2-\pi}
  7. PhysicsJEE Main 6 Apr 2026, Shift 1·Q17·MCQ·Easy–moderate
    Open
    A small cube of side 1 mm is placed at the centre of a circular loop of radius 10 cm carrying a current of 2 A. The magnetic energy stored inside the cube is α×10−14\alpha\times10^{-14} J. The value of α\alpha is . (μ0=4π×10−7\mu_0 = 4\pi\times10^{-7} Tm/A, π=3.14\pi = 3.14)
    1. (1)6.28
    2. (2)6.28×10−66.28\times10^{-6}
    3. (3)628
    4. (4)6.28×10−46.28\times10^{-4}
  8. PhysicsJEE Main 6 Apr 2026, Shift 2·Q13·MCQ·Easy–moderate
    Open
    A current of 30 A each flows in opposite directions in two conducting wires, placed parallel to each other at a distance of 8 cm. The magnetic field at the mid point between the two wires is μ\muT.
    (μ04π=10−7 N/A2\dfrac{\mu_0}{4\pi} = 10^{-7}\ \mathrm{N/A^2})
    1. (1)30
    2. (2)300
    3. (3)150
    4. (4)0.1

Current loop and galvanometer

  1. PhysicsJEE Main 24 Jan 2026, Shift 2·Q13·MCQ·Easy–moderate
    Open
    A moving coil galvanometer of resistance 100 Ω100\ \Omega shows a full scale deflection for a current of 1 mA. The value of resistance required to convert this galvanometer into an ammeter, showing full scale deflection for a current of 5 mA, is Ω\Omega
    1. (1)25
    2. (2)10
    3. (3)0.5
    4. (4)2.5
  2. PhysicsJEE Main 4 Apr 2026, Shift 1·Q12·MCQ·Easy–moderate
    Open
    A voltmeter with internal resistance of x Ωx\ \Omega can be used to measure upto 20 V. In order to increase its measuring range to 30 V, the required modification is to .
    1. (1)connect resistor of x2 Ω\dfrac{x}{2}\,\Omega, in series with voltmeter.
    2. (2)connect resistor of x2 Ω\dfrac{x}{2}\,\Omega, in parallel to voltmeter.
    3. (3)connect resistor of x Ωx\ \Omega, in series with voltmeter.
    4. (4)connect resistor of 2x Ω2x\ \Omega, in parallel to voltmeter.
  3. PhysicsJEE Main 4 Apr 2026, Shift 1·Q16·MCQ·Moderate
    Open
    An insulated wire is wound so that it forms a flat coil with N=200N = 200 turns. The radius of the innermost turn is r1=3r_1 = 3 cm, and of the outermost turn r2=6r_2 = 6 cm. If 20 mA current flows in it then the magnetic moment will be α×10−2 A m2\alpha\times10^{-2}\ \mathrm{A\,m^2}. The value of α\alpha is .
    1. (1)4.4
    2. (2)2.64
    3. (3)3.25
    4. (4)1.2
    We corrected a printing error in the original paper

    Source printed “If 20 mA current flow in it”.

  4. PhysicsJEE Main 4 Apr 2026, Shift 2·Q24·Numerical·Easy–moderate
    Open
    A circular coil of radius 2 cm and 125 turns carries a current of 1 A. The coil is placed in a uniform magnetic field of magnitude 0.4 T. The axis of the coil makes an angle of 30∘30^\circ with the direction of the magnetic field. The torque acting on the coil is α×10−4\alpha\times10^{-4} N.m. The value of α\alpha is . (π=3.14\pi = 3.14)
  5. PhysicsJEE Main 6 Apr 2026, Shift 2·Q23·Numerical·Moderate
    Open
    A moving coil of a galvanometer when shunted with 2 Ω2\ \Omega resistance gives a full scale deflection for a current of 500 mA. When a resistance of 470 Ω470\ \Omega is connected in series it gives a full scale deflection for 10 V potential applied on it. The value of resistance of galvanometer coil is Ω\Omega.
    We corrected a printing error in the original paper

    Source printed “golvanometer”.

  6. PhysicsJEE Main 8 Apr 2026, Shift 2·Q14·MCQ·Easy–moderate
    Open
    A current carrying circular loop of radius 2 cm with unit normal n^=k^+i^2\hat n = \dfrac{\hat k + \hat i}{\sqrt2} is placed in a magnetic field, B⃗=B0(3i^+2k^)\vec B = B_0(3\hat i + 2\hat k). If B0=4×10−3B_0 = 4\times10^{-3} T and current I=1002I = 100\sqrt2 A, the torque experienced by the loop is Wb.A. (π=3.14\pi = 3.14)
    1. (1)16×10−5 k^16\times10^{-5}\,\hat k
    2. (2)5024×10−7 k^5024\times10^{-7}\,\hat k
    3. (3)5024×10−7 i^5024\times10^{-7}\,\hat i
    4. (4)5024×10−7 j^5024\times10^{-7}\,\hat j

Magnetic force

  1. PhysicsJEE Main 21 Jan 2026, Shift 1·Q8·MCQ·Easy–moderate
    Open
    A current carrying solenoid is placed vertically and a particle of mass mm with charge QQ is released from rest. The particle moves along the axis of solenoid. If gg is acceleration due to gravity then the acceleration (aa) of the charged particle will satisfy:
    1. (1)a=ga = g
    2. (2)a>ga > g
    3. (3)a=0a = 0
    4. (4)0<a<g0 < a < g
    We corrected a printing error in the original paper

    Source printed “A current carrying is placed vertically” (“solenoid” missing).

  2. PhysicsJEE Main 28 Jan 2026, Shift 1·Q9·MCQ·Easy–moderate
    Open
    Three long straight wires carrying current are arranged mutually parallel as shown in the figure. The force experienced by 15 cm length of wire QQ is .
    (μ0=4π×10−7\mu_0 = 4\pi\times10^{-7} T.m/A)
    1. (1)6×10−76\times10^{-7} N towards PP
    2. (2)6×10−66\times10^{-6} N towards RR
    3. (3)6×10−76\times10^{-7} N towards RR
    4. (4)6×10−66\times10^{-6} N towards PP
  3. PhysicsJEE Main 2 Apr 2026, Shift 1·Q23·Numerical·Easy–moderate
    Open
    1 μ1\ \muC charge is moving with velocity v⃗=(i^−2j^+3k^)\vec v = \left(\hat i - 2\hat j + 3\hat k\right) m/s in the region of magnetic field B⃗=(2i^+3j^−5k^)\vec B = \left(2\hat i + 3\hat j - 5\hat k\right) T. The magnitude of force acting on it is α×10−6\sqrt\alpha\times10^{-6} N. The value of α\alpha is .
    We corrected a printing error in the original paper

    Source printed “1 μ1\ \muC charge moving with velocity” (no verb).

  4. PhysicsJEE Main 2 Apr 2026, Shift 2·Q4·MCQ·Easy–moderate
    Open
    A particle having charge 10−910^{-9} C moving in xx–yy plane in fields of 0.4 ȷ^0.4\,\hat{\jmath} N/C and 4×10−3 k^4\times10^{-3}\,\hat{k} T experiences a force of (4ı^+2ȷ^)×10−10\left(4\hat{\imath} + 2\hat{\jmath}\right)\times10^{-10} N. The velocity of the particle at that instant is m/s.
    1. (1)50ı^+100ȷ^50\hat{\imath} + 100\hat{\jmath}
    2. (2)100ı^+50ȷ^100\hat{\imath} + 50\hat{\jmath}
    3. (3)−50ı^+100ȷ^-50\hat{\imath} + 100\hat{\jmath}
    4. (4)50ı^−100ȷ^50\hat{\imath} - 100\hat{\jmath}
    We corrected a printing error in the original paper

    Source printed the magnetic field as “4×10−3 k4\times10^{-3}\ k T” (unit vector kk without a hat).

  5. PhysicsJEE Main 5 Apr 2026, Shift 1·Q24·Numerical·Easy–moderate
    Open
    The charged particle moving in a uniform magnetic field of (3i^+2j^)\left(3\hat i + 2\hat j\right) T has an acceleration (4i^−x2j^) m/s2\left(4\hat i - \dfrac{x}{2}\hat j\right)\ \mathrm{m/s^2}. The value of xx is
  6. PhysicsJEE Main 8 Apr 2026, Shift 2·Q23·Numerical·Easy–moderate
    Open
    A 5 mg particle carrying a charge of 5π×10−65\pi\times10^{-6} C is moving with velocity of (3i^+2k^)×10−2(3\hat i + 2\hat k)\times10^{-2} m/s in a region having magnetic field B⃗=0.1 k^ Wb/m2\vec B = 0.1\,\hat k\ \mathrm{Wb/m^2}. It moves a distance of α\alpha meter along k^\hat k when it completes 5 revolutions. The value of α\alpha is .