CBSE Class 10 Science Chapter 13 — Magnetic Effects of Electric Current: NCERT Solutions, Diagrams and 10 MCQs 2027

Last Updated: May 2026

The CBSE Class 10 Magnetic Effects of Electric Current Chapter 13 2027 chapter is one of the most diagram-heavy and concept-heavy units in the Class 10 Science syllabus — typically worth 5 to 6 marks in the 80-mark theory paper and a near-certain source of one full long-answer question with a labelled diagram. This NCERT-rooted guide walks you through every textbook activity, every in-text and exercise question, the right-hand thumb rule, Fleming’s left-hand rule, the working of the electric motor, electromagnetic induction, AC vs DC generator, household wiring and 10 board-pattern MCQs for self-assessment.

Where This Chapter Sits in the 2027 Syllabus

Magnetic Effects of Electric Current is Chapter 13 (in older NCERT it was Chapter 13 of the combined Science textbook; in the rationalised 2024 NCERT, the chapter retains its core experiments — Oersted’s discovery, magnetic field lines, current-carrying conductor, solenoid, force on current-carrying conductor, electric motor, electromagnetic induction, generator and domestic electric circuit). The chapter follows Chapter 12 (Electricity) and naturally extends Oersted’s 1820 discovery that electric current produces a magnetic field. CBSE 2026-27 syllabus weight: approximately 6 marks within the 14-mark Physics block of the 80-mark theory paper.

NCERT Activity vs Board-Frequency Map

The Five Concepts You MUST Master

Concept 1 — Magnetic Field Lines: Lines emerge from N-pole and enter S-pole outside the magnet (and continue from S to N inside). They form closed loops, never intersect, are denser where the field is strong, and are tangent at any point to the field direction. Concept 2 — Right-Hand Thumb Rule: Hold a current-carrying straight conductor in your right hand with the thumb pointing in the direction of current. The curled fingers indicate the direction of the magnetic field lines around the conductor (anticlockwise when current flows toward you, clockwise when current flows away). Concept 3 — Solenoid Field: A solenoid behaves like a bar magnet. Field inside is uniform and parallel to its axis; outside, the field pattern resembles that of a bar magnet. The polarity of either end is determined by the direction of current flow when viewed from that end (anticlockwise = North; clockwise = South). Concept 4 — Fleming’s Left-Hand Rule: Stretch thumb, forefinger and middle finger of the LEFT hand mutually perpendicular. Forefinger = magnetic Field, Middle finger = Current, Thumb = Force/motion. Used for motors. Concept 5 — Fleming’s Right-Hand Rule: Same finger arrangement on the RIGHT hand. Forefinger = Field, Thumb = motion of conductor, Middle finger = induced Current. Used for generators (and generally for the direction of induced current).

Diagram Description — Electric Motor

The DC electric motor consists of: (a) a rectangular coil ABCD of insulated copper wire placed between the poles of a strong permanent magnet; (b) the two ends of the coil are connected to two halves of a split-ring commutator P and Q; (c) the commutator halves rotate with the coil and make sliding contact with two stationary carbon brushes X and Y; (d) the brushes are connected to a battery via a switch. Working: when current flows, side AB of the coil carries current in one direction (say A→B) and side CD in the opposite direction (C→D). By Fleming’s Left-Hand Rule, AB experiences a downward force and CD experiences an upward force — these constitute a couple that rotates the coil. After half a rotation, the split-ring commutator reverses the current direction in the coil, ensuring the rotation continues in the same sense. Function of split-ring: reverses current every half-cycle so the coil rotates continuously in one direction.

Diagram Description — AC vs DC Generator

Both generators consist of an armature coil rotating between the poles of a magnet. The difference is purely in the contact mechanism. AC generator uses two slip rings (separate continuous rings, each connected to one end of the coil) which rotate with the coil and slide against fixed brushes — the induced current flows out, reverses every half-cycle and produces alternating current. DC generator uses a split-ring commutator (a single ring split into two insulated halves, each connected to one end of the coil) — the brush contact switches halves every half-cycle, so the external circuit always sees current in one direction (direct current). The principle in both is electromagnetic induction (Faraday’s law): a changing magnetic flux through the rotating coil induces an EMF.

NCERT Exercise Solutions — Selected Key Problems

Q 1 — Direction of magnetic field at point P due to current-carrying conductor

Apply the right-hand thumb rule. If the current in a straight conductor is upward and point P is to the right of the conductor (when viewed from the front), the magnetic field at P points into the page. Use the curled-fingers convention; the field circulates around the conductor.

Q 7 — When is force on a current-carrying conductor in a magnetic field maximum?

The force F = BIL sin θ, where θ is the angle between the conductor and the magnetic field direction. F is maximum when θ = 90° — that is, when the conductor is perpendicular to the magnetic field. F is zero when θ = 0° or 180° (conductor parallel or antiparallel to field).

Q 11 — State the rule used to find the direction of force on a current-carrying conductor

Fleming’s Left-Hand Rule. Stretch thumb, forefinger and middle finger of the left hand mutually perpendicular. Forefinger = direction of magnetic field, middle finger = direction of current, thumb = direction of force/motion of the conductor.

Q 14 — Why are coils of electric toaster and electric iron made of alloy and not pure metal?

Two reasons: (i) Alloys (like nichrome — Ni, Cr, Fe, Mn) have higher resistivity than pure metals, so they produce more heat per unit current (P = I²R). (ii) Alloys do not oxidise (burn) readily at high temperatures, giving the heating element a longer life.

Q 16 — Functions of an earth wire

The earth wire (green-insulated) connects the metal body of an appliance to the ground via a copper plate buried in moist earth. If by accident a live wire touches the metal body, the earth wire provides a low-resistance path for the current to flow into the ground, preventing the user from receiving a shock. Without earthing, the body of the appliance would become live and any user touching it would complete a circuit through their body.

Key Formulas to Memorise

• Force on a current-carrying conductor: F = B × I × L × sin θ. Maximum when θ = 90°.
• Magnetic field of a solenoid (qualitative): uniform inside, similar to a bar magnet outside.
• Frequency of AC in India: 50 Hz. Each cycle has 2 polarity changes; current direction reverses 100 times per second.
• Domestic supply voltage in India: 220 V (live to neutral); the live wire carries current and is colour-coded red/brown; the neutral wire is colour-coded black/blue; the earth wire is colour-coded green/yellow.
• Fuse rating: a fuse melts when the current exceeds its rated value. Common household fuses: 5 A (lighting circuits), 15 A (heavy-appliance circuits like geyser, AC).
• Short circuit: when the live and neutral wires touch directly (insulation broken), resistance drops to near-zero, and a very large current flows, blowing the fuse.
• Overloading: when too many high-power appliances are connected to the same circuit, the total current exceeds the fuse rating and the fuse blows.

Internal Resources for Class 10 Science 2027

• Ready For Boards Class 10 Science course — chapter-wise concepts, NCERT solutions, sample papers
• CBSE 2027 hub — Class 10 syllabus, marking pattern, sample papers
• Free resources — formula sheets, board-paper analyses, quick-revision notes
• CBSE FAQ — exam pattern, internal assessment, practical exam guidelines
• Sample papers — Class 10 Science 2027 board-pattern model papers

Common Errors That Cost Marks

The first is mixing up Fleming’s Left-Hand and Right-Hand rules. Left-hand = motors (force on current). Right-hand = generators (induced current from motion). The simple memory hook: motors use the same hand as "Left" → you push the lever (force); generators "give" current from the "Right". The second is the function of split-ring vs slip-rings — split-ring reverses current direction (used in DC motors and DC generators); slip-rings do NOT reverse current (used in AC generators only). The third is forgetting that magnetic field lines always form closed loops, never open-ended. The fourth is direction of magnetic field around a current-carrying conductor — always apply the right-hand thumb rule explicitly; never guess. The fifth is colour-coding of household wires (live = red/brown, neutral = black/blue, earth = green/yellow) — frequently asked as a 1-mark MCQ.

10 Board-Pattern MCQs (Self-Test)

FAQ — CBSE Class 10 Magnetic Effects of Electric Current 2027

How many marks does this chapter carry in CBSE Class 10 Boards?

Approximately 6 marks in the 80-mark theory paper, distributed as 1 MCQ (1 mark) + 1 short-answer (3 marks) + 1 long-answer or case-based (3-5 marks). The chapter is part of the 14-mark Physics block (Electricity Ch 12 + Magnetic Effects Ch 13).

What is the rationalised 2024 NCERT version of this chapter?

The 2024 rationalised NCERT retains the core experiments — Oersted’s discovery, magnetic field lines, right-hand thumb rule, solenoid, force on current-carrying conductor, electric motor, electromagnetic induction, generator and domestic circuits. Some descriptive activity content has been pruned but the essential concept set is intact and aligned with the board exam.

Which diagram is most asked in board exams from this chapter?

The labelled diagram of the DC electric motor (with armature, brush, split-ring commutator, magnet poles labelled) is the single most-asked diagram, appearing in roughly 4 of the last 5 board papers. The AC vs DC generator comparison diagram is the second-most-asked.

What is the difference between a fuse and a Miniature Circuit Breaker (MCB)?

A fuse is a thin wire that melts when current exceeds its rated value, breaking the circuit (one-time use; replace after blowing). An MCB is an automatic switch that "trips" (breaks) when current exceeds rating but can be reset by flipping the switch back. MCBs are more convenient and are now standard in modern Indian homes.

How do I revise this chapter quickly before the board?

One day before: revise magnetic field lines and right-hand thumb rule (15 min), Fleming’s Left and Right Hand Rules with one-line memory hooks (20 min), DC motor diagram with labels (30 min), AC vs DC generator comparison (20 min), domestic circuit colour-codes and earth-wire function (15 min). Then solve one previous-year long-answer question (45 min). Roughly two and a half hours of focused revision is enough.

Closing — Practise, Revise, Score

Master the five concepts, internalise the diagrams, drill the rules, and solve every NCERT exercise question at least twice with proper labelled diagrams. The Ready For Boards Class 10 Science course includes chapter-wise concept videos, NCERT-line-by-line solutions, weekly chapter tests and full-length board-pattern model papers. Build your foundation here and Physics becomes one of the highest-scoring sections of your Class 10 paper.