Magnetic Effects of Current and Magnetism — NEET Physics MCQs with answers

Magnetic Effects of Current and Magnetism is a Class 12 Physics chapter in the NEET (UG) syllabus. NEET720 has 936 reviewed practice questions on it, each with a quick answer and a step-by-step explanation. The 8 questions below are free and fixed, so you can bookmark this page; the full chapter, plus mistake tracking and spaced revision, is in the app.

Topics covered

Biot-Savart law and applications · Ampere's law and solenoids · Force on moving charges · Force on current-carrying conductors · Torque on current loops and galvanometer · Bar magnet and magnetic dipole · Magnetic materials · Applications of electromagnets · Galvanometer conversion · Motion of a charged particle in a magnetic field · Applications of Ampere's law · Earth's magnetism and charged particle motion · Synthesis across magnetism topics · Motion of Charges in Magnetic Fields · Solenoid and Toroid · Magnetic Dipole · Biot-Savart law and applications · Force on a moving charge · Earth's Magnetism · Torque on a current loop · Biot-Savart law · Magnetic field due to straight wire · Gauss's Law for Magnetism · Magnetic field due to circular loop · Bar magnet and magnetic dipole · Ampere's circuital law · Magnetic field of solenoid · Magnetic dipole in a uniform field · Magnetic field of toroid · Magnetic materials · Force on moving charge · Motion of charged particle in magnetic field · Magnetic field energy · Force between parallel wires · Magnetic flux · Force and torque on current loop · Moving coil galvanometer · Magnetic dipole moment · Bar magnet as equivalent solenoid · Magnetic field lines

8 free Magnetic Effects of Current and Magnetism practice questions with answers

Choose an answer in your head before opening it. Each explanation says why the correct option is right and, where relevant, why the tempting wrong option is wrong.

1. Question 1 · easy · Biot-Savart law and applications

   A long straight vertical wire carries current flowing vertically upward. At a point P located due east of the wire, at the same height, the magnetic field due to the wire points

   • A.toward the south
   • B.toward the north
   • C.vertically upward, parallel to the wire
   • D.directly away from the wire, radially outward
   Show answer and explanation

   Answer: B. toward the north

   Using the right-hand rule (thumb up along current), the field circles the wire; at a point east of the wire, the field points north.

   Grip the wire with the right hand, thumb pointing in the direction of current (upward). The fingers curl in the direction of B. Standing at a point due east of the wire and looking at the wire, the curling fingers point toward north at that location (the field lines are horizontal circles around the vertical wire). This is a standard right-hand-rule application distinct from Coulomb's radial field.

   Common mistake: Treating the magnetic field as radial like an electric field, instead of circular

2. Question 2 · medium · Galvanometer conversion

   Why must an ideal ammeter have very low resistance while an ideal voltmeter must have very high resistance?

   • A.An ammeter is placed in series in the circuit and must not appreciably change the current it measures, whereas a voltmeter is placed in parallel across a component and must draw negligible current so as not to alter the voltage across it
   • B.An ammeter is placed in parallel and a voltmeter in series, so their resistance requirements follow directly from Ohm's law with no other reasoning needed
   • C.Both requirements exist purely to protect the galvanometer coil from overheating, unrelated to circuit loading effects
   • D.High resistance in an ammeter and low resistance in a voltmeter would give more accurate readings, but manufacturing constraints prevent this
   Show answer and explanation

   Answer: A. An ammeter is placed in series in the circuit and must not appreciably change the current it measures, whereas a voltmeter is placed in parallel across a component and must draw negligible current so as not to alter the voltage across it

   An ammeter (in series) must have negligible resistance so it doesn't reduce the circuit current; a voltmeter (in parallel) must have very high resistance so it draws negligible current and doesn't alter the voltage being measured.

   An ammeter is always connected in series with the branch whose current is being measured. If its resistance were significant, inserting it would itself reduce the current in that branch (by adding extra resistance to the loop), giving an inaccurate reading — hence it must have resistance as close to zero as possible. A voltmeter, by contrast, is connected in parallel across the component whose voltage is being measured. If its resistance were low, it would draw significant current away from the component (act as a partial short), changing the very voltage it's trying to measure — hence it must have resistance as high as possible so it draws negligible current and leaves the circuit undisturbed. Both requirements stem from the same principle: minimise the meter's disturbance to the circuit under test.

   Common mistake: Swapping the series/parallel placement or the corresponding resistance requirement for ammeter and voltmeter

3. Question 3 · medium · Galvanometer conversion

   A student says: "An ideal ammeter should have as large a resistance as possible so it can accurately measure large currents without being damaged." Is this correct?

   • A.Yes, exactly as stated — high resistance is what allows an ammeter to handle large currents safely
   • B.No — an ideal ammeter should have resistance approaching zero, so that inserting it in series barely changes the current already flowing in the circuit
   • C.No — an ideal ammeter should have resistance equal to the resistance of the component whose current is being measured
   • D.Yes, but only for AC circuits; for DC circuits low resistance is preferred
   Show answer and explanation

   Answer: B. No — an ideal ammeter should have resistance approaching zero, so that inserting it in series barely changes the current already flowing in the circuit

   An ammeter is placed in series in a circuit, so it must have negligible resistance to avoid altering the very current it is meant to measure; a low-resistance shunt achieves this.

   An ammeter is inserted in series with the circuit branch whose current is to be measured. If the ammeter itself had significant resistance, adding it in series would reduce the actual current flowing (by increasing total circuit resistance), so the reading would not reflect the original, undisturbed current. An ideal ammeter therefore has zero resistance; a real ammeter (galvanometer + low shunt) is designed to have as small a resistance as practically possible, which is precisely why the shunt is chosen to be much smaller than the galvanometer resistance.

   Common mistake: Confusing 'able to carry large current' with 'should have large resistance'

4. Question 4 · easy · Magnetic materials

   A small rod of bismuth is suspended freely between the poles of a strong magnet. It slowly aligns itself perpendicular to the magnetic field. This behaviour is characteristic of which class of magnetic material?

   • A.Ferromagnetic
   • D.Diamagnetic
   • C.Paramagnetic
   • B.Antiferromagnetic
   Show answer and explanation

   Answer: D. Diamagnetic

   Bismuth is diamagnetic; diamagnetic substances are weakly repelled by a magnetic field and a freely suspended rod turns perpendicular to the field to minimise flux through it.

   Diamagnetic materials have no net atomic magnetic moment; an applied field induces a small moment opposite to the field (Lenz's law at atomic level), so they are weakly repelled. A freely suspended diamagnetic rod therefore settles with its length perpendicular to the field to minimise the flux linked through it, unlike paramagnetic/ferromagnetic rods which align along the field. Bismuth is a classic strongly diamagnetic element used in this demonstration.

   Common mistake: Assuming any alignment in a magnetic field must be 'along the field' as in paramagnets

5. Question 5 · easy · Magnetic materials

   Which of these is the key distinguishing feature between a paramagnetic and a ferromagnetic material?

   • A.Only ferromagnetic materials have a net magnetic moment per atom, paramagnetic atoms have none
   • B.Paramagnetic materials are repelled by a magnet, ferromagnetic materials are attracted
   • C.In ferromagnetic materials neighbouring atomic moments align spontaneously into domains due to strong exchange interaction, giving large magnetisation even without an external field, unlike paramagnetic materials
   • D.Ferromagnetic susceptibility is negative while paramagnetic susceptibility is positive
   Show answer and explanation

   Answer: C. In ferromagnetic materials neighbouring atomic moments align spontaneously into domains due to strong exchange interaction, giving large magnetisation even without an external field, unlike paramagnetic materials

   Ferromagnetism arises from strong exchange coupling that spontaneously aligns atomic moments into domains, giving large magnetisation even with no external field — paramagnetic moments align only weakly and randomise without a field.

   Both paramagnetic and ferromagnetic atoms possess permanent atomic magnetic moments (ruling out A). Both are attracted by a magnetic field, not repelled (ruling out B), and both have positive susceptibility (ruling out D). The real distinction is the exchange interaction: in ferromagnets it is strong enough to align neighbouring moments into domains spontaneously, producing large magnetisation that can persist without an external field; in paramagnets the moments are only weakly and independently aligned by the field and randomise by thermal agitation once the field is removed.

   Common mistake: Believing susceptibility sign or attraction/repulsion (rather than domain formation) is what separates para from ferro

6. Question 6 · medium · Magnetic materials

   A student claims: "Since diamagnetic materials are repelled by a magnetic field, they must have a permanent atomic magnetic moment that points opposite to the applied field." Is this reasoning correct?

   • A.Yes, diamagnetic atoms have a fixed moment permanently anti-parallel to any applied field
   • B.No — diamagnetic atoms have no net permanent magnetic moment; the field itself induces a small opposing moment (via Lenz's-law-like electron orbital response) only while the field is applied
   • C.No — diamagnetism has nothing to do with magnetic moments; it is purely a mechanical effect of the material's density
   • D.Yes, and this permanent opposing moment also exists in paramagnetic materials, just weaker
   Show answer and explanation

   Answer: B. No — diamagnetic atoms have no net permanent magnetic moment; the field itself induces a small opposing moment (via Lenz's-law-like electron orbital response) only while the field is applied

   Diamagnetism arises from an induced (not permanent) opposing moment created only in the presence of an external field, by electromagnetic induction at the atomic scale — it disappears once the field is removed.

   This is a classic misconception: diamagnetic atoms have zero net permanent magnetic moment in the absence of a field (all electron orbital and spin moments cancel). When an external field is switched on, it changes the orbital motion of electrons (analogous to an induced EMF opposing flux change, per Lenz's law), inducing a small magnetic moment opposite to the applied field. This induced moment exists only while the field is present and vanishes when it is removed — unlike paramagnetic/ferromagnetic materials, which possess genuine permanent atomic moments that merely align with (rather than being created by) the field.

   Common mistake: Believing diamagnetic repulsion implies a fixed permanent opposing moment, like a tiny bar magnet flipped backwards

7. Question 7 · easy · Magnetic materials

   A small piece of aluminium is brought near one pole of a strong bar magnet. What happens to it?

   • A.It is weakly attracted toward the pole
   • B.It is weakly repelled from the pole
   • C.It is strongly attracted, almost like iron
   • D.It shows no interaction at all with the magnet
   Show answer and explanation

   Answer: A. It is weakly attracted toward the pole

   Aluminium is paramagnetic: its atoms have a small net magnetic moment that weakly aligns with an external field, producing weak attraction toward stronger-field regions.

   Paramagnetic materials (Al, Na, Ca, O2) have atoms/ions with unpaired electrons giving a small permanent magnetic moment. In an external field these moments partially align with the field (opposed by thermal agitation), giving a small net magnetisation in the same direction as B. Since the material tends to move toward stronger field regions when magnetised parallel to the field, aluminium is weakly attracted toward the pole. This is much weaker than ferromagnetic attraction (option C) and opposite in direction to diamagnetic repulsion (option B).

   Common mistake: Confusing paramagnetic weak attraction with diamagnetic repulsion

8. Question 8 · easy · Magnetic materials

   Which of the following is a correct microscopic reason why all materials, even paramagnetic and ferromagnetic ones, exhibit some diamagnetism?

   • A.Diamagnetism only exists in atoms that have no electrons at all
   • B.Diamagnetism arises from orbital motion of electrons, which occurs in every atom regardless of whether it also has unpaired-electron spin moments
   • C.Diamagnetism is caused by the nucleus spinning oppositely to the applied field
   • D.Diamagnetism appears only in materials cooled below their Curie temperature
   Show answer and explanation

   Answer: B. Diamagnetism arises from orbital motion of electrons, which occurs in every atom regardless of whether it also has unpaired-electron spin moments

   Diamagnetism is a universal, weak, essentially temperature-independent effect from the induced (Lenz's-law-like) change in orbital electron motion, present in every atom.

   Every atom has electrons in orbital motion, and Lenz's law implies that an applied field induces a small change in this orbital motion that opposes the applied field, giving a tiny diamagnetic moment in every material. In paramagnetic and ferromagnetic materials this universal diamagnetic contribution is present but is completely masked by the much larger effect of unpaired-electron (spin) moments aligning with the field. Hence diamagnetism is a background effect in all matter, not something restricted to a special class of atoms.

   Common mistake: Thinking diamagnetism is a distinct 'either/or' category rather than a universal underlying effect

Questions about Magnetic Effects of Current and Magnetism for NEET

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Questions are original NEET720 compositions reviewed for correctness, syllabus fit and option quality. Counts update as the bank grows (936 active practice questions in this chapter today).