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CBSE Class 10 Physics Chapters 2026-27: Light, the Human Eye, Electricity and Magnetism
The CBSE Class 10 physics chapters for 2026-27 are four NCERT chapters: Light – Reflection and Refraction; The Human Eye and the Colourful World; Electricity; and Magnetic Effects of Electric Current. In the official CBSE Science syllabus they form two units, Natural Phenomena (12 marks) and Effects of Current (13 marks), so physics carries 25 of the 80 theory marks. Motors, electromagnetic induction and the electric generator are in the syllabus but assessed only in school, not in the year-end paper.
This guide is part of our Class 10 home tutors in Gurgaon series. For each of the class 10 physics chapters in the CBSE course, it gives the syllabus, key ideas, diagrams to practise and worked numericals we have checked step by step, then the commonest mistakes and the link to Class 11 and 12 physics.
Which physics chapters are in CBSE Class 10 Science 2026-27
Physics has no separate Class 10 syllabus; it sits inside Science (code 086). The official CBSE Science syllabus for Class X (2026-27) groups the physics content into two units. The NCERT Class 10 Science textbook covers the same content in four chapters, numbered 9 to 12.
| CBSE unit (2026-27) | Marks | NCERT chapter | What the syllabus lists |
|---|---|---|---|
| Unit III: Natural Phenomena | 12 | Chapter 9: Light – Reflection and Refraction | Spherical mirrors and the images they form; mirror formula (derivation not required); magnification. Laws of refraction; refractive index. Spherical lenses; lens formula (derivation not required); power of a lens. |
| Chapter 10: The Human Eye and the Colourful World | Functioning of the lens in the human eye; defects of vision and their correction; applications of spherical mirrors and lenses. Refraction through a prism, dispersion, scattering of light and daily-life applications (excluding the colour of the sun at sunrise and sunset). | ||
| Unit IV: Effects of Current | 13 | Chapter 11: Electricity | Current, potential difference, Ohm's law; resistance and resistivity; series and parallel resistors; heating effect of current; electric power and the relation between P, V, I and R. |
| Chapter 12: Magnetic Effects of Electric Current | Magnetic field and field lines; field due to a current-carrying conductor, a coil and a solenoid; force on a current-carrying conductor; Fleming's left-hand rule; direct current; alternating current and its frequency; advantage of AC over DC; domestic electric circuits. |
What is assessed only in school
The 2026-27 syllabus lists three Unit IV topics as "assessed only formatively": motor, electromagnetic induction and electric generator. They remain in the syllabus but do not add to the year-end examination; schools may assess them through periodic tests or the portfolio.
The syllabus also says the information boxes in the NCERT textbooks ("More to Know" and similar) will not be assessed in the year-end examination. The "Note for Teachers" at the end words the Unit IV exclusion differently; we follow the unit box, but if your school reads it differently, follow the school.
For the chemistry and biology units, and the full Science practical list, see our guide to the CBSE Class 10 Science syllabus 2026-27.
Marks, paper design and internal assessment
Physics is worth 25 of the 80 theory marks in Class 10 Science: 12 for Natural Phenomena and 13 for Effects of Current. The other units are Chemical Substances (25), World of Living (25) and Natural Resources (5). The theory paper is 3 hours long, and internal assessment adds 20 marks, for a total of 100.
The internal assessment of 20 marks is split into periodic assessment (5), multiple assessment (5), portfolio (5) and subject enrichment, which is practical work (5). According to the question paper design in the same document, the theory paper has about 50% questions that test knowledge and understanding, 30% that test application, and 20% that ask students to analyse, evaluate or create. Question types include objective and assertion–reasoning questions, short and long answers, and source-based or case-based questions, with an internal choice of about 33%.
In physics, the numericals sit mostly in the application band, and case-based questions often pair a short passage with a numerical.
Light: reflection and refraction
This is the longest of the four physics chapters and the one with the most numericals. It covers spherical mirrors, refraction, lenses and the power of a lens.
Key ideas
- New Cartesian sign convention: distances are measured from the pole (or optical centre); those along the incident light are positive, those against it negative, and heights above the axis positive. With the object on the left, u is negative.
- Mirror formula: 1/v + 1/u = 1/f, with R = 2f. Magnification for a mirror is m = h′/h = −v/u.
- Lens formula: 1/v − 1/u = 1/f. Magnification for a lens is m = h′/h = v/u. Note the two formulas differ in sign; mixing them up is the most common error in this chapter.
- Focal length signs: a concave mirror and a concave lens have negative focal lengths; a convex mirror and a convex lens have positive focal lengths.
- Refraction: sin i / sin r is constant for a pair of media (Snell's law); the refractive index is n = c/v.
- Power of a lens: P = 1/f, with f in metres, in dioptres (D).
- Sign of m: negative means real and inverted; positive means virtual and erect.
Worked numerical 1: An object is placed 20 cm in front of a concave mirror of focal length 15 cm. Find the position, nature and magnification of the image.
Answer: v = −60 cm; the image is real, inverted and three times the size of the object. With the sign convention, u = −20 cm and f = −15 cm. From 1/v + 1/u = 1/f: 1/v = 1/f − 1/u = −1/15 + 1/20 = (−4 + 3)/60 = −1/60, so v = −60 cm. The image is 60 cm in front of the mirror. Magnification m = −v/u = −(−60)/(−20) = −3. Check: the object is between F and C, so the image should be beyond C, real and enlarged.
Worked numerical 2: A convex mirror used as a rear-view mirror has a focal length of 20 cm. A car is 30 cm from the mirror. Where is the image, and how big is it compared with the car?
Answer: v = +12 cm; the image is virtual, erect and 0.4 times the size of the object. Here u = −30 cm and f = +20 cm. So 1/v = 1/20 − (−1/30) = 1/20 + 1/30 = 5/60 = 1/12, giving v = +12 cm, behind the mirror. m = −v/u = −12/(−30) = +0.4. A convex mirror always gives a virtual, erect, diminished image, hence its wide field of view.
Worked numerical 3: A 2 cm tall object is placed 15 cm from a convex lens of focal length 10 cm. Find the position and size of the image.
Answer: v = +30 cm; image height −4 cm (real, inverted, twice the size). u = −15 cm, f = +10 cm. From 1/v − 1/u = 1/f: 1/v = 1/f + 1/u = 1/10 − 1/15 = 1/30, so v = +30 cm, on the other side of the lens. Magnification for a lens is m = v/u = 30/(−15) = −2, so the image height is h′ = m × h = −2 × 2 = −4 cm. The minus sign tells you the image is below the axis, that is, inverted. Trap: using m = −v/u (the mirror formula) here gives +2 and the wrong nature of image.
Worked numerical 4: An object is 30 cm from a concave lens of focal length 15 cm. Find the image position, the magnification and the power of the lens.
Answer: v = −10 cm; m = +1/3; P ≈ −6.67 D. u = −30 cm, f = −15 cm. So 1/v = 1/f + 1/u = −1/15 − 1/30 = −3/30 = −1/10, and v = −10 cm: the image is on the same side as the object, virtual and erect. m = v/u = (−10)/(−30) = +1/3. Power P = 1/f with f in metres: 1/(−0.15) ≈ −6.67 D. Trap: putting f = −15 (in centimetres) into P = 1/f, which gives a meaningless −0.067.
Worked numerical 5: The refractive index of a glass is 1.5. Find the speed of light in it (c = 3 × 108 m/s). If the refractive index of crown glass is 1.52 and of water is 1.33, find the refractive index of crown glass with respect to water.
Answer: 2 × 108 m/s; about 1.14. From n = c/v, v = c/n = (3 × 108)/1.5 = 2 × 108 m/s. The refractive index of medium 2 with respect to medium 1 is n21 = n2/n1, so glass with respect to water is 1.52/1.33 ≈ 1.14.
From our tutors: in mirror and lens numericals, we ask students to write the four signed values (u, v or "unknown", f and h) in a small table before touching the formula, and then to sketch a rough ray diagram to check the answer. Most wrong answers we see come from a misplaced sign, not weak algebra, and the sketch catches them in seconds.
The human eye and the colourful world
This chapter applies lens ideas to the eye, then explains dispersion and scattering. It has few numericals but many diagram and explanation questions.
Key ideas
- The eye as a lens system: light enters through the cornea; the eye lens forms a real, inverted image on the retina. The ciliary muscles change the lens's focal length, which is called accommodation.
- Near and far points: for a young adult with normal vision, the near point (least distance of distinct vision) is about 25 cm, and the far point is at infinity.
- Myopia (near-sightedness): the far point is closer than infinity and the image of a distant object forms in front of the retina. It is corrected with a concave lens of suitable power.
- Hypermetropia (far-sightedness): the near point is farther than 25 cm and the image of a near object would form behind the retina. It is corrected with a convex lens.
- Prism and dispersion: a prism bends light twice, towards its base; different colours bend by different amounts, so white light splits into a spectrum. Violet bends the most and red the least.
- Scattering: very fine particles scatter shorter (bluer) wavelengths more, which is why the clear sky looks blue. The 2026-27 syllabus excludes the colour of the sun at sunrise and sunset.
Worked numerical 6: A student with myopia cannot see clearly beyond 80 cm. What kind of lens, and of what power, will correct this?
Answer: a concave lens of power −1.25 D. The correcting lens must form a virtual image of a very distant object (u at infinity) at the student's far point, v = −80 cm. With 1/v − 1/u = 1/f and 1/u = 0, f = v = −80 cm = −0.8 m. So P = 1/f = 1/(−0.8) = −1.25 D. The negative power confirms a concave (diverging) lens.
Electricity
Electricity is the most numerical of the class 10 physics chapters in CBSE Science. Nearly every question reduces to Ohm's law, resistor combinations and the power relations.
Key ideas
- Ohm's law: V = IR, at constant temperature. The V–I graph for an ohmic resistor is a straight line through the origin; its slope is R.
- Resistivity: R = ρL/A. Resistivity ρ depends on the material and temperature, not on the wire's shape.
- Series: Rs = R1 + R2 + …; the same current flows through each resistor, and the voltage divides.
- Parallel: 1/Rp = 1/R1 + 1/R2 + …; the voltage is the same across each branch, and the current divides.
- Heating effect (Joule's law): H = I2Rt. Uses include electric irons, heaters and the fuse.
- Power: P = VI = I2R = V2/R. The commercial unit of energy is the kilowatt hour: 1 kWh = 3.6 × 106 J, called one "unit" on an electricity bill.
Worked numerical 7: A wire of resistivity 1.6 × 10−8 Ω m is 10 m long and has a cross-sectional area of 1 × 10−6 m2. Find its resistance. What happens to the resistance if the same wire is stretched to twice its length?
Answer: 0.16 Ω; it becomes four times as large, 0.64 Ω. R = ρL/A = (1.6 × 10−8 × 10)/(1 × 10−6) = 0.16 Ω. When the wire is stretched, its volume stays the same, so doubling the length halves the area. R = ρ(2L)/(A/2) = 4ρL/A, four times the original. Trap: answering "twice", which forgets that the area also changes.
Worked numerical 8: Resistors of 4 Ω and 12 Ω are connected in parallel, and this pair is connected in series with a 3 Ω resistor across a 12 V battery. Find the total resistance, the current from the battery and the current in each parallel branch.
Answer: 6 Ω; 2 A; 1.5 A through 4 Ω and 0.5 A through 12 Ω. For the parallel pair, 1/Rp = 1/4 + 1/12 = 4/12, so Rp = 3 Ω. Total R = 3 + 3 = 6 Ω, and I = V/R = 12/6 = 2 A. The voltage across the parallel pair is 2 × 3 = 6 V, so the current through 4 Ω is 6/4 = 1.5 A and through 12 Ω is 6/12 = 0.5 A. Check: 1.5 + 0.5 = 2 A, the total current. Trap: dividing the 12 V of the battery across the 4 Ω resistor directly, ignoring the 3 Ω in series.
Worked numerical 9: A 1500 W room heater is used for 2 hours a day for 30 days on a 220 V supply. How many units of electrical energy does it use? What current does it draw, and should it be on a 5 A or a 15 A circuit?
Answer: 90 units (kWh); about 6.8 A; the 15 A circuit. Energy = power × time = 1.5 kW × (2 × 30) h = 90 kWh, or 90 units. Current I = P/V = 1500/220 ≈ 6.8 A. This is more than 5 A, so the heater belongs on the higher-rated circuit used for heavy appliances. Trap: multiplying 1500 W by 60 h and reporting 90,000 without converting watts to kilowatts.
Worked numerical 10: Two bulbs rated 100 W, 220 V and 60 W, 220 V are connected in series across a 220 V supply. Which glows brighter?
Answer: the 60 W bulb. First find each bulb's resistance from its rating, R = V2/P: 2202/100 = 484 Ω and 2202/60 ≈ 806.7 Ω. In series the same current flows through both: I = 220/(484 + 806.7) ≈ 0.17 A. Power in each is I2R: about 14.1 W in the 100 W bulb and 23.4 W in the 60 W bulb. The bulb with the larger resistance dissipates more power in series, so the 60 W bulb glows brighter. In parallel (as at home), each gets the full 220 V and the 100 W bulb is brighter.
From our tutors: for any resistor network, we ask students to redraw the circuit first, simplifying it one step at a time and writing the equivalent resistance next to each step, before finding any current. Then they check that the currents at every junction add up. Students who try to do this in their head lose marks even when they know the formulas.
Is your child confident with formulas but still losing marks in ray diagrams or circuit numericals? Book a free Class 10 Science demo with Ajay Vatsyayan Classes. Our tutor will work through a few questions with your child and show you exactly where the marks are slipping.
Book a Free Class 10 Science Demo +91 92204 75088Magnetic effects of electric current
This chapter is about field patterns and directions rather than calculation.
Key ideas
- Magnetic field lines: they emerge from the north pole and enter the south pole outside a magnet, form closed loops, and never cross. Where they are closer together, the field is stronger.
- Straight conductor: the field lines are concentric circles around the wire. The right-hand thumb rule gives the direction: thumb along the current, fingers curl in the direction of the field. The field weakens with distance from the wire.
- Circular loop: the lines are nearly straight at the centre; the field grows with the number of turns and the current.
- Solenoid: the field inside is nearly uniform, with parallel lines, and outside it resembles a bar magnet. A soft iron core inside a solenoid makes an electromagnet.
- Force on a conductor: a current-carrying conductor in a magnetic field experiences a force, largest when the current is perpendicular to the field. Fleming's left-hand rule gives its direction: forefinger along the field, middle finger along the current, thumb along the force.
- DC and AC: direct current flows in one direction; alternating current reverses direction periodically. In India, the domestic supply is AC at 220 V and 50 Hz, according to the NCERT textbook. An advantage of AC is that it can be transmitted over long distances with less energy loss.
- Domestic circuits: live (red), neutral (black) and earth (green) wires; the fuse protects against overloading and short-circuits; earthing protects users of metal-bodied appliances.
Worked direction question: A horizontal wire carries current from south to north. What is the direction of the magnetic field just above the wire, and just below it?
Answer: east above the wire; west below it. Point the right thumb north along the current. Looking along the wire from the south end, the fingers curl clockwise: over the top of the wire towards the east (your right), and under the bottom towards the west.
Motor, electromagnetic induction and the generator are assessed only in school in 2026-27, as described above. Students who plan to take Science in Class 11 should still read them: electromagnetic induction is a full unit of Class 12 physics.
Diagrams to practise
Ray diagrams and field diagrams carry marks on their own, and a neat diagram often earns part marks even when the explanation is thin. These are the ones we ask students to practise until they can draw them from memory, with arrows, labels and a ruler.
| Chapter | Diagram | What examiners look for |
|---|---|---|
| Light | Concave mirror, object at six positions: at infinity, beyond C, at C, between C and F, at F, between F and P | At least two correct rays per diagram (for example, parallel to the axis then through F; through C and back along itself); arrows on every ray; image position and nature |
| Light | Convex lens, object at the same six positions; concave lens, two positions | Ray through the optical centre undeviated; ray parallel to the axis refracted through (or appearing to come from) the focus |
| Light | Refraction through a rectangular glass slab | Normal at both faces; emergent ray parallel to the incident ray; angles i, r and e marked; lateral displacement shown |
| Human eye | Myopia and hypermetropia, with and without the correcting lens | Image position relative to the retina; far point or near point marked; correct lens type |
| Human eye | Refraction through a triangular prism; dispersion of white light | Angle of deviation marked; red at the top and violet at the bottom of the spectrum |
| Electricity | Circuit with cell, key, resistor, ammeter in series and voltmeter in parallel | Standard symbols; ammeter in series, voltmeter across the resistor |
| Magnetic effects | Field lines of a bar magnet, a straight wire, a circular loop and a solenoid | Closed loops, no crossings, arrows from N to S outside the magnet; uniform lines inside a solenoid |
| Magnetic effects | Fleming's left-hand rule; a domestic circuit | Three mutually perpendicular directions labelled; live, neutral and earth wires, fuse and meter shown |
The five physics experiments in the 2026-27 practical list use the same diagrams: the V–I graph for a resistor, resistors in series and parallel, the focal length of a concave mirror and a convex lens, and tracing rays through a glass slab and a prism.
Common mistakes in Class 10 physics
These are the mistakes our Home Tutors Team sees most often when marking Class 10 physics answers, alongside missing arrows on rays and missing units.
- Mixing the mirror and lens formulas. The mirror formula has a plus sign (1/v + 1/u = 1/f) and mirror magnification a minus sign (m = −v/u). The lens formula has a minus sign (1/v − 1/u = 1/f) and lens magnification no minus sign (m = v/u).
- Forgetting that u is negative. With the object on the left, u is negative in nearly every CBSE problem.
- Putting centimetres into P = 1/f. Power in dioptres needs the focal length in metres.
- Stating the wrong lens for a defect. Myopia needs a concave lens; hypermetropia needs a convex lens. Write the reason (image in front of or behind the retina) alongside.
- Combining resistors in the wrong order. Simplify the innermost series or parallel group first and redraw the circuit.
- Using the rated power of a bulb in a new circuit. A bulb's rating gives its resistance (R = V2/P); its actual power depends on the circuit it is placed in.
- Swapping the left-hand and right-hand rules. The right-hand thumb rule gives the field around a current; Fleming's left-hand rule gives the force on a conductor.
How marks are awarded for steps, diagrams and units is covered in our guide to CBSE Class 10 answer writing.
How Class 10 physics prepares for Class 11 and 12
If your child is thinking about taking physics in Class 11, these four chapters matter beyond the board exam. According to the CBSE Physics (Classes XI–XII) syllabus for 2026-27, Class 11 physics is mostly mechanics, heat and waves, while the topics of Class 10 physics come back, in much more depth, in Class 12.
| Class 10 chapter | Where it returns (CBSE 2026-27) | What carries forward |
|---|---|---|
| Light – Reflection and Refraction | Class 12, Unit VI: Optics | Sign convention, mirror and lens formulas, power; Class 12 adds total internal reflection, the lens-maker's formula and optical instruments |
| The Human Eye and the Colourful World | Class 12, Unit VI: Optics | Refraction through a prism, dispersion, scattering; optical instruments build on how the eye forms images |
| Electricity | Class 12, Units I–II: Electrostatics; Current Electricity | Ohm's law, resistivity, series and parallel combinations, power; Class 12 adds drift velocity, Kirchhoff's rules and the Wheatstone bridge |
| Magnetic Effects of Electric Current | Class 12, Units III–IV: Magnetic Effects of Current and Magnetism; Electromagnetic Induction and Alternating Currents | Field patterns and the hand rules; induction, assessed only in school in Class 10, becomes a full unit |
Class 11 physics does not repeat these chapters, but it relies on the habits they build: a strict sign convention (the same idea is used for displacement and velocity in kinematics), reading and drawing graphs such as V–I, clean unit handling, and the discipline of drawing before calculating. Our guide to mechanics for JEE physics shows how much of Class 11 depends on those habits. If your child is still weighing up subjects, our guide on which stream to choose after Class 10 sets out the options neutrally.
A study plan for the physics chapters
- Light first, slowly. Learn the sign convention before any formula. Draw every standard ray diagram, then solve ten mirror and ten lens numericals.
- The human eye next, while lenses are fresh. Make the myopia–hypermetropia comparison table and practise the prism and eye diagrams.
- Electricity: Ohm's law and resistivity, then combinations, then heating and power. Do the two practical experiments (V–I graph and series–parallel resistance) alongside.
- Magnetic effects: draw the four field patterns and practise direction questions with both hand rules.
- Mixed revision: alternate a light set with an electricity set so that students do not forget the first chapter while learning the third.
- Previous papers: once the chapters are done, solve CBSE's own papers chapter by chapter, checking the marking schemes. Our guide to CBSE Class 10 previous year question papers explains how.
Students in Gurgaon and across Gurugram often juggle school tests and projects; it is better to finish light properly than to rush all four chapters.
Frequently asked questions
How many physics chapters are there in CBSE Class 10 Science?
Four NCERT chapters: Light – Reflection and Refraction; The Human Eye and the Colourful World; Electricity; and Magnetic Effects of Electric Current. In the CBSE 2026-27 syllabus they make up Unit III (Natural Phenomena) and Unit IV (Effects of Current).
How many marks is physics in Class 10 CBSE?
25 of the 80 theory marks in 2026-27: 12 for Natural Phenomena and 13 for Effects of Current. Science also has 20 marks of internal assessment, which covers all three sciences.
Is the electric motor in the Class 10 syllabus for 2026-27?
It is in the syllabus, but CBSE says motor, electromagnetic induction and the electric generator will be assessed only formatively, in school, and will not add to the year-end examination. Check with your child's school how it assesses them.
Is "Sources of Energy" a Class 10 physics chapter?
No. It is not listed in the CBSE Class X Science syllabus for 2026-27. The physics content is limited to the two units described in this guide.
Do I need to learn derivations of the mirror and lens formulas?
No. The 2026-27 syllabus states "derivation not required" for both the mirror formula and the lens formula. Students need to use them correctly with the sign convention.
Can a home tutor help with Class 10 physics?
Yes. One-to-one, a tutor can watch how a student sets up signs, draws rays and simplifies circuits, where most physics marks are lost. Our Home Tutors Team teaches Class 10 Science at home in Gurgaon or online.
Want the four physics chapters taught in the right order, with every ray diagram and circuit checked? Book a free Class 10 Science demo with Ajay Vatsyayan Classes, Saraswati kunj II, Wazirabad, Sector 52, Gurugram, Haryana 122003. Male and female tutors are available, at home or online.
Book a Free Class 10 Science Demo +91 92204 75088