JEE Main Physics · Magnetism PYQ

JEE Main Magnetism & Moving Charges PYQ (2002–2025)

Magnetism & Moving Charges is a P1 Electromagnetism chapter — ~5% JEE Main weightage with 1–2 questions per session. Numerical-heavy and vector-driven, builds on Electrostatics and bridges into EMI/AC. Biot-Savart and Ampere's law calculations recur year-on-year.

Magnetism PYQs from 2002 to 2025 tagged by sub-topic (force on charge, force on current, magnetic field from sources, cyclotron, galvanometer). Every solution includes the vector setup.

Practise Magnetism & Moving Charges PYQs All Physics PYQs

Magnetism & Moving Charges at a Glance

Weightage

~5%

approx · 10-yr avg

Priority

Must master

Year range

2002–2025

PYQ coverage

Typical in paper

1–2

per session

Key Sub-Topics & What's Tested

Magnetic Force on Charge

F = qv × B, motion of charged particle in uniform B field (circular path), radius r = mv/(qB), time period T = 2πm/(qB).

Magnetic Force on Current-Carrying Conductor

F = IL × B, force between two parallel current-carrying wires (F/L = μ₀I₁I₂/(2πd)).

Biot-Savart Law

dB = (μ₀/4π) × (I dl × r̂)/r², applications: B at centre of circular loop, B on axis of loop, B due to straight wire.

Ampere's Circuital Law

∮B·dl = μ₀I_enc, applications: B due to infinite wire, solenoid (B = μ₀nI), toroid.

Magnetic Field due to Solenoid / Toroid

Solenoid interior: B = μ₀nI uniform; outside ≈ 0. Toroid: B = μ₀NI/(2πr). Both derivable from Ampere's law.

Cyclotron

Frequency f = qB/(2πm), kinetic energy at exit K = q²B²R²/(2m), independent of charge speed at injection.

Magnetic Dipole

Torque τ = m × B, potential energy U = -m·B, m = IA for current loop, Bar magnet as dipole.

Moving Coil Galvanometer

Current sensitivity (θ/I), voltage sensitivity, conversion to ammeter (shunt) and voltmeter (high series resistance).

Question Type Distribution

Question Type	Share (approx)	Example Pattern
Magnetic Force Calculation	25%	Find force on a wire of length 1m carrying 5A current in a 0.2T field perpendicular to wire.
Circular Motion in B-Field	20%	Electron enters a 0.5T field perpendicular to velocity — find radius of circular path.
Biot-Savart Application	15%	Find magnetic field at centre of a circular loop of radius R carrying current I.
Ampere's Law Application	15%	Find B inside a solenoid with n turns/m carrying current I.
Cyclotron Problem	10%	Find the frequency of cyclotron for proton in a 1T field.
Galvanometer Conversion	15%	Galvanometer has full-scale deflection at 10mA, resistance 100Ω — find shunt for 1A ammeter.

How to Solve Magnetism & Moving Charges PYQs

1
Master the three field-source formulas. Circular loop at centre: B = μ₀I/(2R). Infinite wire: B = μ₀I/(2πd). Solenoid: B = μ₀nI. Know all three exactly.
2
Use right-hand rule consistently. F = qv × B direction: right-hand rule with fingers v → B → F. Wrong direction is the #1 magnetism mistake.
3
Circular motion: r = mv/(qB). For charged particle in perpendicular B, the radius formula alone handles most cyclic-motion PYQs.
4
Ampere's law needs symmetry. Apply only when you can find a closed path where B is uniform and tangential. For non-symmetric cases, use Biot-Savart.
5
Galvanometer conversion: current in shunt = full-scale current × resistance ratio. Master the shunt/series resistor formulas — standard template.

Common Mistakes That Cost Marks

Missing vector nature of F = qv × B. Force is perpendicular to both v and B. If v ∥ B (parallel), F = 0 (no force on charge moving along field).
Wrong radius formula in non-uniform fields. r = mv/(qB) only works for uniform perpendicular B. Non-perpendicular gives helical motion.
Confusing μ₀ in CGS vs SI units. Always use SI: μ₀ = 4π × 10⁻⁷ T·m/A. Don't mix with CGS formulas.
Applying Ampere's law without closed path. The integral is ∮B·dl around a closed loop. Open paths don't qualify.
Galvanometer shunt confusion. For ammeter, shunt is in parallel (to divert large current). For voltmeter, high resistance is in series. Don't swap.

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Frequently asked questions

How many Magnetism PYQs should I solve?

Target 60–80 PYQs across 2010–2025. ~5% weightage with high template repeat — focused practice reaches strong accuracy in ~40 hours.

Is Magnetism harder than Electrostatics?

Slightly — adds vector/cross product complexity. Electrostatics is dot products; Magnetism is cross products with right-hand rule. But templates are similar. Master Electrostatics first, then Magnetism follows.

Do I need to memorise cyclotron formulas?

Yes — f = qB/(2πm), K_exit = q²B²R²/(2m). These appear directly in 2-3 PYQs per decade. Short chapter, easy to memorise.

What's the most-tested Magnetism PYQ pattern?

Charged particle in perpendicular magnetic field — circular motion problems. Appears in 4-5 PYQs per 10-year window. Master r = mv/(qB).

Does Magnetism connect with EMI/AC?

Yes — EMI is about changing magnetic flux induced EMF. Strong Magnetism fluency directly accelerates EMI problem-solving.

Are magnetic materials (para/dia/ferro) tested?

Minimally in JEE Main — 1 PYQ per 4-5 years on material classification. Focus on field-from-current problems and magnetic force problems.

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