What does Magnetic Effects of Current and Magnetism cover for NEET Physics?

18 lessons: Ammeter Voltmeter Conversion, Ampere's Law, Ampere's Law Solenoid, Ampere's Law Straight Wire, Bar Magnet As Solenoid, Biot Savart Circular Loop, Biot Savart Law, Current Loop Dipole Moment, Definition of Ampere, Force Between Parallel Currents, Force on Current Conductor, Lorentz Force on Charge, Magnetic Field of Dipole, Moving Coil Galvanometer, Para Dia Ferromagnetic, Temperature Effect Magnetic Properties, Torque Current Loop and Torque Magnetic Dipole.

How often has Magnetic Effects of Current and Magnetism come up in NEET past papers?

Our set of verified past papers has 17 questions from this unit, from NEET 2020, 2021, 2022, 2023, 2024, 2025 and 2026. Each is answered against the official NTA key.

Is the Magnetic Effects of Current and Magnetism material free?

Yes. All 18 lessons and 144 practice questions are free, with no login needed.

Magnetic Effects of Current and Magnetism

18 lessons

Topic index in NCERT order

18 of 18 lessons by the NCERT chapter they teach from, in book order. The page is the first printed page of your NCERT book the lesson cites; PYQs are the past NEET questions on that topic.

Class 12 Physics, Chapter 4

Lorentz Force on Chargep. 1091 PYQ
Force on Current Conductorp. 1101 PYQ
Biot Savart Lawp. 1142 PYQs
Biot Savart Circular Loopp. 1164 PYQs
Ampere's Lawp. 1180 PYQs
Ampere's Law Straight Wirep. 1201 PYQ
Ampere's Law Solenoidp. 1222 PYQs
Definition of Amperep. 1230 PYQs
Force Between Parallel Currentsp. 1231 PYQ
Current Loop Dipole Momentp. 1260 PYQs
Torque Current Loopp. 1260 PYQs
Ammeter Voltmeter Conversionp. 1300 PYQs
Moving Coil Galvanometerp. 1300 PYQs

Class 12 Physics, Chapter 5

Bar Magnet As Solenoidp. 1391 PYQ
Magnetic Field of Dipolep. 1412 PYQs
Torque Magnetic Dipolep. 1410 PYQs
Para Dia Ferromagneticp. 1472 PYQs
Temperature Effect Magnetic Propertiesp. 1480 PYQs

Ammeter Voltmeter Conversion

8 MCQsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Ampere's Law

8 MCQs3 revision cardsWorked example

Easy Recall (2)Concept Trap (2)Direct Application (2)Calculation (2)

Ampere's Law Solenoid

8 MCQs2 PYQs1 revision cardWorked example

Easy Recall (2)Direct Application (2)Concept Trap (2)Calculation (2)

Ampere's Law Straight Wire

8 MCQs1 PYQs1 revision cardWorked example

Easy Recall (2)Direct Application (2)Concept Trap (2)Calculation (2)

Bar Magnet As Solenoid

8 MCQs1 PYQs4 revision cardsWorked example

Easy Recall (2)Direct Application (2)Concept Trap (2)Calculation (2)

Biot Savart Circular Loop

8 MCQs4 PYQs1 revision cardWorked example

Easy Recall (2)Direct Application (3)Concept Trap (1)Calculation (2)

Biot Savart Law

8 MCQs2 PYQs1 revision cardWorked example

Easy Recall (2)Direct Application (2)Concept Trap (2)Calculation (2)

Current Loop Dipole Moment

8 MCQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Definition of Ampere

8 MCQs2 revision cardsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (2)

Force Between Parallel Currents

8 MCQs1 PYQs1 revision cardWorked example

Easy Recall (2)Direct Application (3)Concept Trap (1)Calculation (2)

Force on Current Conductor

8 MCQs1 PYQs2 revision cardsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Lorentz Force on Charge

8 MCQs1 PYQs4 revision cardsWorked example

Easy Recall (3)Direct Application (3)Calculation (2)

Magnetic Field of Dipole

8 MCQs2 PYQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Calculation (1)Concept Trap (1)

Moving Coil Galvanometer

8 MCQs2 revision cardsWorked example

Easy Recall (2)Concept Trap (2)Direct Application (2)Calculation (2)

Para Dia Ferromagnetic

8 MCQs2 PYQsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Temperature Effect Magnetic Properties

8 MCQs3 revision cardsWorked example

Easy Recall (3)Direct Application (3)Calculation (1)Concept Trap (1)

Torque Current Loop

8 MCQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Calculation (2)

Torque Magnetic Dipole

8 MCQsWorked example

Easy Recall (3)Direct Application (3)Calculation (2)

Past-paper questions from this unit

17 questions from NEET 2020, 2021, 2022, 2023, 2024, 2025, 2026. Answers verified against NTA official keys.

By year in our set: 2020 (1) · 2021 (1) · 2022 (3) · 2023 (3) · 2024 (5) · 2025 (2) · 2026 (2)

Lesson: Biot Savart Circular Loop

NEET 2026

A current I₀ flows through a metallic circular loop of radius r as shown in the figure. Resistance of the segment ABC is half that of ADC. Magnitude of magnetic field at the center O of the loop is :

1μ₀I₀/12r

2μ₀I₀/4r

3μ₀I₀/2r

4μ₀I₀/2πr

NTA Answer: Option 1(final)

Report an error · Every fix is public: corrections log

Lesson: Force Between Parallel Currents

NEET 2026

Two infinitely long parallel conducting wires A and B carry currents I and 2I, respectively, in the same direction. The wire A has uniform mass per unit length λ and lies on an insulated floor. The wire B is kept fixed at a height h above the floor. The minimum magnitude of h so that the wire A does not rise from the floor is : [g is the acceleration due to gravity and μ₀ is the permeability of free space.]

1μ₀I²/(2πλg)

2μ₀I²/(πλg)

32μ₀I²/(πλg)

44μ₀I²/(πλg)

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Lesson: Lorentz Force on Charge

NEET 2025

An electron (mass 9 × 10⁻³¹ kg and charge 1.6 × 10⁻¹⁹ C) moving with speed c/100 (c = speed of light) is injected into a magnetic field B⃗ of magnitude 9 × 10⁻⁴ T perpendicular to its direction of motion. We wish to apply an uniform electric field E⃗ together with the magnetic field so that the electron does not deflect from its path. Then (speed of light c = 3 × 10⁸ m s⁻¹)

1E⃗ is parallel to B⃗ and its magnitude is 27 × 10⁴ V m⁻¹

2E⃗ is perpendicular to B⃗ and its magnitude is 27 × 10⁴ V m⁻¹

3E⃗ is perpendicular to B⃗ and its magnitude is 27 × 10² V m⁻¹

4E⃗ is parallel to B⃗ and its magnitude is 27 × 10² V m⁻¹

NTA Answer: Option 3(final)

Report an error · Every fix is public: corrections log

Lesson: Biot Savart Circular Loop

NEET 2025

A 2 amp current is flowing through two different small circular copper coils having radii ratio 1 : 2. The ratio of their respective magnetic moments will be

14 : 1

21 : 4

31 : 2

42 : 1

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Lesson: Magnetic Field of Dipole

NEET 2024Revised key

In a uniform magnetic field of 0.049 T, a magnetic needle performs 20 complete oscillations in 5 seconds as shown. The moment of inertia of the needle is 9.8 x 10⁻⁶ kg m². If the magnitude of magnetic moment of the needle is x × 10⁻⁵ Am2, then the value of ‘x’ is :

15π2

2128π2

350π2

41280π2

NTA Answer: Option 4(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Biot Savart Circular Loop

NEET 2024Revised key

A tightly wound 100 turns coil of radius 10 cm carries a current of 7A. The magnitude of the magnetic field at the centre of the coil is (Take permeability of free space as 4π × 10⁻⁷ SI units):

144 mT

24.4 T

34.4 mT

444 T

NTA Answer: Option 3(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Para Dia Ferromagnetic

NEET 2024Revised key

Match List-I with List-II. List-I List-II (Material) (Susceptibility (χ)) A. Diamagnetic I. χ = 0 B. Ferromagnetic II. 0 > χ ≥ –1 C. Paramagnetic III. χ >> 1 D. Non-magnetic IV. 0 < χ < ε (a small positive number) Choose the correct answer from the options given below

1A-II, B-III, C-IV, D-I

2A-II, B-I, C-III, D-IV

3A-III, B-II, C-I, D-IV

4A-IV, B-III, C-II, D-I

NTA Answer: Option 1(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Para Dia Ferromagnetic

NEET 2024Revised key

A sheet is placed on a horizontal surface in front of a strong magnetic pole. A force is needed to: A. hold the sheet there if it is magnetic. B. hold the sheet there if it is non-magnetic. C. move the sheet away from the pole with uniform velocity if it is conducting. D. move the sheet away from the pole with uniform velocity if it is both, non-conducting and non-polar. Choose the correct statement(s) from the options given below:

1B and D only

2A and C only

3A, C and D only

4C only

NTA Answer: Option 2(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Bar Magnet As Solenoid

NEET 2024Revised key

An iron bar of length L has magnetic moment M. It is bent at the middle of its length such that the two arms make an angle 60° with each other. The magnetic moment of this new magnet is :

2M/2

32M

4M/√3

NTA Answer: Option 2(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Magnetic Field of Dipole

NEET 2023

The net magnetic flux through any closed surface is

1Positive

2Infinity

3Negative

4Zero

NTA Answer: Option 4(final)

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Lesson: Force on Current Conductor

NEET 2023

A wire carrying a current I along the positive x-axis has length L. It is kept in a magnetic field B⃗ = (2î + 3ĵ − 4k̂) T. The magnitude of the magnetic force acting on the wire is

1√5 IL

25 IL

3√3 IL

43 IL

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Lesson: Biot Savart Circular Loop

NEET 2023

A very long conducting wire is bent in a semi-circular shape from A to B as shown in figure. The magnetic field at point P for steady current configuration is given by

1(μ₀i/4R) pointed away from the page

2(μ₀i/4R)[1 − 2/π] pointed away from page

3(μ₀i/4R)[1 − 2/π] pointed into the page

4(μ₀i/4R) pointed into the page

NTA Answer: Option 2(final)

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Lesson: Biot Savart Law

NEET 2022

Given below are two statements Statement I : Biot-Savart’s law gives us the expression for the magnetic field strength of an infinitesimal current element (Idl) of a current carrying conductor only. Statement II : Biot-Savart’s law is analogous to Coulomb’s inverse square law of charge q, with the former being related to the field produced by a scalar source, Idl while the latter being produced by a vector source, q. In light of above statements choose the most appropriate answer from the options given below

1Statement I is incorrect and Statement II is correct

2Both Statement I and Statement II are correct

3Both Statement I and Statement II are incorrect

4Statement I is correct and Statement II is incorrect

NTA Answer: Option 4(final)

Report an error · Every fix is public: corrections log

Lesson: Ampere's Law Solenoid

NEET 2022

A long solenoid of radius 1 mm has 100 turns per mm. If 1 A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is

16.28 × 10⁻⁴ T

26.28 × 10⁻² T

312.56 × 10⁻² T

412.56 × 10⁻⁴ T

NTA Answer: Option 3(final)

Report an error · Every fix is public: corrections log

Lesson: Ampere's Law Straight Wire

NEET 2022

From Ampere’s circuital law for a long straight wire of circular cross-section carrying a steady current, the variation of magnetic field in the inside and outside region of the wire is

1A linearly decreasing function of distance upto the boundary of the wire and then a linearly increasing one for the outside region.

2Uniform and remains constant for both the regions.

3A linearly increasing function of distance upto the boundary of the wire and then linearly decreasing for the outside region.

4A linearly increasing function of distance r upto the boundary of the wire and then decreasing one with 1 r dependence for the outside region.

NTA Answer: Option 4(final)

Report an error · Every fix is public: corrections log

Lesson: Biot Savart Law

NEET 2021

A uniform conducting wire of length 12a and resistance 'R' is wound up as a current carrying coil in the shape of, (i) an equilateral triangle of side 'a'. (ii) a square of side 'a'. The magnetic dipole moments of the coil in each case respectively are

14 Ia² and 3 Ia²

2√3 Ia² and 3 Ia²

33 Ia² and Ia²

43 Ia² and 4 Ia²

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Lesson: Ampere's Law Solenoid

NEET 2020

A long solenoid of 50 cm length having 100 turns carries a current of 2.5 A. The magnetic field at the centre of the solenoid is : (µ0=4π×10⁻⁷ T m A⁻¹)

13.14×10⁻⁵ T

26.28×10⁻⁴ T

33.14×10⁻⁴ T

46.28×10⁻⁵ T

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Exam traps and common mistakes in this unit

Lesson: Ampere's Law Straight Wire

Trap

Long-wire vs circular-loop B formula confusion

Category: Similar Terms

Student uses μ_0 I/(2πr) (straight wire) when asked about circular loop centre (μ_0 I/(2R)) — or vice versa.

When it triggers

Magnetic field magnitude question with specific geometry (straight wire, loop, solenoid).

How to avoid

Straight wire: B = μ_0 I/(2πr) at perpendicular distance r. Circular loop centre: B = μ_0 I/(2R). Solenoid: B = μ_0 nI. Match formula to geometry.

Lesson: Ampere's Law Solenoid

Mistake

Uses total turns N instead of turns-per-length n in solenoid formula.

Root cause: formula misuse

Correction

B = μ_0 n I where n = N/L (turns per metre). If N=100 over 50 cm, then n=200/m and B = μ_0 × 200 × I.

Lesson: Ampere's Law Straight Wire

Mistake

Uses straight-wire formula for circular loop centre (or vice versa).

Root cause: formula misuse

Correction

Straight wire (long, infinite): B = μ_0 I/(2πr). Circular loop, centre: B = μ_0 I/(2R). The 'π' is in straight-wire; missing in loop.

Formulas in this unit

Lesson: Ampere's Law

Ampere's circuital law

\oint B \cdot d l = μ_{0} I_{enc}

Line integral of B around closed loop = mu0 x current enclosed.

Symbol	Quantity	SI Unit
I_enc	current enclosed	A
mu0	permeability	T*m/A

Valid when

Steady current (Maxwell-Ampere needed if displacement current present)
Closed Amperian loop

Lesson: Ampere's Law Solenoid

B inside long solenoid

B = μ_{0} n I

Uniform field inside long solenoid; n = turns per unit length. Approximately zero outside.

Symbol	Quantity	SI Unit
n	turns per metre	1/m
I	current	A

Valid when

Long solenoid (length >> radius)
Tightly wound

Lesson: Ampere's Law Straight Wire

B near long straight wire

B = \frac{μ _{0} I}{2 π r}

Field at perpendicular distance r from infinite straight wire carrying I.

Symbol	Quantity	SI Unit
B	field	T
I	current	A
r	perp distance	m

Valid when

Wire >> r (effectively infinite)
r > wire radius

Lesson: Biot Savart Circular Loop

B at centre of circular loop

B = \frac{μ _{0} I}{2 R}

Magnetic field at centre of circular current loop of radius R carrying current I.

Symbol	Quantity	SI Unit
B	field	T
I	current	A
R	loop radius	m

Valid when

Single loop
At loop centre

Lesson: Biot Savart Law

Biot-Savart law

d B = \frac{μ _{0}}{4 π} \frac{I d l \times r ^}{r ^{2}}

Magnetic field from current element. mu0 = 4*pi*10^-7 T*m/A.

Symbol	Quantity	SI Unit
I	current	A
dl	element length	m
r	distance	m
mu0	permeability	T*m/A

Valid when

Steady current
Free space

Lesson: Current Loop Dipole Moment

Torque on current loop

τ = m \times B

Torque on N-turn loop of area A carrying I in field B; magnetic moment m = NIA.

Symbol	Quantity	SI Unit
N	turns	-
A	loop area	m^2
B	field	T
m	magnetic moment	A*m^2
theta	angle between m and B	rad

Valid when

Uniform B
Loop in plane

Lesson: Definition of Ampere

Force between parallel currents

\frac{F}{L} = \frac{μ _{0} I _{1} I _{2}}{2 π d}

Force per unit length between long parallel wires separated by d. Same direction → attractive.

Symbol	Quantity	SI Unit
I1, I2	currents	A
d	separation	m

Valid when

Long parallel wires
Steady currents

Lesson: Force on Current Conductor

Force on current-carrying wire

F = I L \times B

Force on straight current-carrying wire of length L in field B. Theta = angle between L and B.

Symbol	Quantity	SI Unit
I	current	A
L	length	m
B	field	T
theta	angle	rad

Valid when

Uniform B
Straight wire

Lesson: Lorentz Force on Charge

Cyclotron radius / period

r = \frac{m v}{q B}; T = \frac{2 π m}{q B}

Charge q moves in circle of radius r in uniform B perpendicular to v. Period independent of v.

Symbol	Quantity	SI Unit
r	radius	m
T	period	s
m	mass	kg
v	speed	m/s
q	charge	C
B	field	T

Valid when

v ⊥ B
Uniform B
Non-relativistic

Lesson: Lorentz Force on Charge

Lorentz force

F = q (E + v \times B)

Total force on charge q in electric and magnetic fields. Magnetic part always perpendicular to v.

Symbol	Quantity	SI Unit
F	force	N
q	charge	C
E	electric field	V/m
v	velocity	m/s
B	magnetic field	T

Valid when

Point particle
Non-relativistic

Lesson: Magnetic Field of Dipole

Magnetic dipole field (axial/equatorial)

B_{ax} = \frac{μ _{0}}{4 π} \frac{2 m}{r ^{3}}; B_{eq} = \frac{μ _{0}}{4 π} \frac{m}{r ^{3}}

Magnetic field from dipole moment m at distance r along axis or equatorial.

Symbol	Quantity	SI Unit
m	dipole moment	A*m^2
r	distance	m

Valid when

r >> dipole size
Far-field approximation

NEET question patterns in this unit

Lesson: Ampere's Law Solenoid

Long solenoid: B = mu_0 n I. Plug in turns/m and current.

Direct ApplicationEasy

Common distractors

uses total N not n

Forgets to divide by length

Lesson: Ampere's Law Straight Wire

Field from long straight wire: B = mu_0 I/(2 pi r).

Direct ApplicationEasy

Common distractors

forgets pi in denominator

Confuses with circular loop formula

Lesson: Biot Savart Circular Loop

Field at centre of circular loop: B = mu_0 I / (2R).

Direct ApplicationEasy

Common distractors

forgets 2 in denominator

Uses mu_0 I/R instead of mu_0 I/(2R)

Lesson: Lorentz Force on Charge

Charge in uniform B (perpendicular to v): r = mv/(qB). Compute radius or speed.

Multi StepMedium

Common distractors

forgets charge or mass in formula

Drops m or q from r formula

Lesson: Magnetic Field of Dipole

Magnetic dipole field at axial / equatorial point. Axial 2m/r^3, equatorial m/r^3.

InterpretationMedium

Common distractors

uses axial formula equatorial

Mixes axial 2m vs equatorial m factor

Questions about this unit

What does Magnetic Effects of Current and Magnetism cover for NEET Physics?: 18 lessons: Ammeter Voltmeter Conversion, Ampere's Law, Ampere's Law Solenoid, Ampere's Law Straight Wire, Bar Magnet As Solenoid, Biot Savart Circular Loop, Biot Savart Law, Current Loop Dipole Moment, Definition of Ampere, Force Between Parallel Currents, Force on Current Conductor, Lorentz Force on Charge, Magnetic Field of Dipole, Moving Coil Galvanometer, Para Dia Ferromagnetic, Temperature Effect Magnetic Properties, Torque Current Loop and Torque Magnetic Dipole.
How often has Magnetic Effects of Current and Magnetism come up in NEET past papers?: Our set of verified past papers has 17 questions from this unit, from NEET 2020, 2021, 2022, 2023, 2024, 2025 and 2026. Each is answered against the official NTA key.
Is the Magnetic Effects of Current and Magnetism material free?: Yes. All 18 lessons and 144 practice questions are free, with no login needed.