Practice tests · NEET

NEET Magnetic Effects of Current and Magnetism: 5 practice MCQs

By the PrepMatic team · Updated 9 Oct 2026 · 4 min read

This NEET unit combines two NCERT Class 12 chapters: the magnetic effects of electric current (Moving Charges and Magnetism) and the magnetism of materials (Magnetism and Matter). The five MCQs below test the field of a circular loop, force on a moving charge, a charged particle's circular path, a solenoid and the Curie temperature.

What this chapter covers in the NEET syllabus

The NMC unit is titled Magnetic Effects of Current and Magnetism. Its topics, following the NCERT chapters, are:

• Biot-Savart law, the field of a straight wire, a circular loop and a solenoid, and Ampere's circuital law.
• Force on a moving charge in magnetic and combined electric and magnetic fields, and the circular path of a charged particle.
• Force on a current-carrying conductor, force between parallel currents, and the torque on a loop.
• The moving coil galvanometer and its conversion to an ammeter or voltmeter.
• Bar magnet, magnetic dipole moment, Earth's magnetism and magnetic elements.
• Dia-, para- and ferromagnetic materials, and the Curie temperature.

Five practice MCQs on Magnetism

Question 1

A circular loop of radius 10 cm carries a current of 5 A. The magnetic field at its centre is (μ₀ = 4π × 10⁻⁷ T m/A):

• A. π × 10⁻⁵ T
• B. 2π × 10⁻⁵ T
• C. π × 10⁻⁶ T
• D. 4π × 10⁻⁷ T

Question 2

A charged particle moves parallel to a uniform magnetic field. The magnetic force on the particle is:

• A. qvB
• B. qvB/2
• C. zero
• D. qB/v

Question 3

A proton and an alpha particle enter a uniform magnetic field perpendicular to it with the same speed. The ratio of the radii of their circular paths, r(proton) : r(alpha), is:

• A. 2 : 1
• B. 1 : 2
• C. 1 : 1
• D. 1 : 4

Question 4

A long solenoid has 1000 turns per metre and carries a current of 2.5 A. The magnetic field inside it is (μ₀ = 4π × 10⁻⁷ T m/A):

• A. 4π × 10⁻⁴ T
• B. 2π × 10⁻³ T
• C. 4π × 10⁻⁷ T
• D. π × 10⁻³ T

Question 5

Above its Curie temperature, a ferromagnetic material behaves as a:

• A. paramagnetic substance
• B. diamagnetic substance
• C. superconductor
• D. stronger ferromagnet

Answers and explanations

1. A. For a loop of one turn, B = μ₀I/2R = (4π × 10⁻⁷ × 5)/(2 × 0.1) = (2π × 10⁻⁶)/0.2 = π × 10⁻⁵ T. Convert the radius to metres first.
2. C. The force is F = qvB sin θ, where θ is the angle between v and B. For parallel motion θ = 0, so the force is zero and the particle's speed and direction stay unchanged.
3. B. The radius is r = mv/qB. For the same v and B, r is proportional to m/q. For a proton m/q = m/e. For an alpha particle (mass 4m, charge 2e) it is 4m/2e = 2m/e. So r(proton) : r(alpha) = 1 : 2.
4. D. Inside a long solenoid B = μ₀nI = 4π × 10⁻⁷ × 1000 × 2.5 = 4π × 10⁻⁷ × 2500 = π × 10⁻³ T. Here n is turns per unit length, so no further division by length is needed.
5. A. Thermal agitation destroys the alignment of domains at the Curie temperature, so the material becomes paramagnetic. Heating a magnet above this temperature removes its permanent magnetism.

How to prepare Magnetism

• Learn the right-hand rules as a set. One for the field around a wire, one for the direction of force (F = qv × B), and one for a coil's polarity. Practise sketching them on each question until you stop second-guessing.
• Keep the standard field formulas in one list: straight wire μ₀I/2πr, circular loop centre μ₀I/2R, solenoid μ₀nI, and the field at the axis of a loop. Know that fields from different wires add as vectors.
• Remember what a magnetic force can and cannot do. It does no work, so it changes direction but not speed. A particle at an angle to the field follows a helix.
• Understand conversion of a galvanometer. A shunt in parallel makes an ammeter, and a high resistance in series makes a voltmeter. The formulas are short, and the questions are direct.
• Tabulate material properties. For dia-, para- and ferromagnets, list susceptibility sign, effect of temperature and examples.

Spend a day on the Biot-Savart and Ampere results, and another on charged particles and materials. See the NEET Physics preparation guide for subject-level order and the NEET syllabus for the full list.

Take a full Magnetism test on PrepMatic

The rules and formulas in this unit are easy to mix up, so test them under time pressure. A PrepMatic topic test is about 15 questions in 30 minutes, with NEET's negative marking in the score. The free Basic plan includes topic tests, and the practice hub lists other chapters.

← All practice tests