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Class XII · Physics

Magnetic Effects of Current and Magnetism: NEET MCQ practice

286 practice questions on Magnetic Effects of Current and Magnetism, each with an explanation. Practise them chapter by chapter in the GyaanLoop app.

286

Practice questions

127

Easy

154

Medium

5

Hard

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What Magnetic Effects of Current and Magnetism covers

Topics in the NEET (UG) 2026–27 syllabus for this chapter.

  • Biot-Savart law and Ampere's law, current carrying circular loop and solenoid
  • Force on a moving charge and on a current-carrying conductor in a magnetic field
  • Torque on a current loop, moving coil galvanometer and conversion to ammeter/voltmeter
  • Bar magnet as an equivalent solenoid, magnetic field lines, magnetic dipole moment
  • Torque on a magnetic dipole in a uniform magnetic field
  • Para-, dia- and ferromagnetic substances, effect of temperature on magnetic properties

Sample questions on Magnetic Effects of Current and Magnetism

Try each one, then open the answer and explanation.

Question 1 · Practice question

Ratio of magnetic force F m and electric force F e acting on a charge getting undeflected through the field is

  1. A.E/B
  2. B.B/E
  3. C.1
  4. D.0
Show answer

Answer: C. 1

For the charge to go undeflected, the magnetic force and electric force must cancel each other, meaning their magnitudes are equal, so the ratio Fₘ/Fₑ = 1. Option (a) E/B is the speed v for undeflected motion, not the force ratio. Option (b) B/E is the inverse of that speed. Option (d) 0 would mean no magnetic force, which generally wouldn't balance an electric force for undeflected motion.

Question 2 · Practice question

Time taken by an ion to describe a semicircular path, in a cyclotron

  1. A.Depends upon the electric field.
  2. B.depends upon the radius of the circular path.
  3. C.depends upon speed of ion.
  4. D.is constant.
Show answer

Answer: D. is constant.

In a cyclotron, the magnetic force provides the centripetal force: qvB = mv²/r → r = mv/(qB). The time for a semicircle is half the full cyclotron period: t = πm/(qB), which depends only on ion mass, charge, and magnetic field strength, not on speed or radius. Thus, as the ion accelerates, its speed and radius increase but the semicircular time stays constant. Option (a) is incorrect because the electric field accelerates the ion but does not influence semicircular motion time; (b) and (c) are wrong since radius and speed increase together, but the time is independent of both.

Question 3 · Practice question

The dipole moment of a current loop is independent of:

  1. A.magnetic field of the loop.
  2. B.current in the loop
  3. C.area of the loop
  4. D.number of turns
Show answer

Answer: A. magnetic field of the loop.

The magnetic dipole moment of a current loop is defined as N I A – it depends on number of turns, current and area, but does not depend on the magnetic field produced by the loop itself. The magnetic field is an effect of the dipole moment, not a factor in its definition.

Question 4 · Practice question

If cathode rays are projected at right angles to a magnetic field, their trajectory is

  1. A.Ellipse
  2. B.Circle
  3. C.Parabola
  4. D.None of these
Show answer

Answer: B. Circle

Cathode rays are electrons moving with a constant speed. When projected perpendicular to a uniform magnetic field, the magnetic force acts as a centripetal force, causing them to move in a circle. The parabola option is a common distractor because students may confuse it with the motion in an electric field or under gravity.

Question 5 · Practice question

Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as. Assertion (A): Magnetic poles cannot be separated by breaking a bar magnet into two pieces. Reason (R): When a magnet is broken into two pieces, the magnetic moment will be reduced to half.

  1. A.A. Both A and R are true and R is the correct explanation of A
  2. B.B. Both A and R are true but R is NOT the correct explanation of A
  3. C.C. A is true but R is false
  4. D.D. A is false and R is true
Show answer

Answer: B. B. Both A and R are true but R is NOT the correct explanation of A

Both statements are factually correct: breaking a bar magnet always yields two smaller magnets each with its own poles (A true), and breaking it into two equal pieces reduces the magnetic moment to half (R true). However, R does not explain A; the reason magnetic poles cannot be separated relates to the absence of magnetic monopoles, not the halving of magnetic moment.

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