CBSE EXAM CLASS 12TH LATEST UPDATE

Finally, wait is over and Central Board of Secondary Education (CBSE) has announced class 12 Board exams date. This year class 12th board exam will be started from 15 February 2025 and will last upto 04 April 2025, it will take around 49 days to complete the class 12th board exam. The first exam will be held on 15 February 2025 for Entrepreneurship (Including Vocational Students) subject and the last exam will be held on 04 April 2025 for Psychology subject. The practical exams/Internal Assesment/Projects & the board’s annual theory examinations are scheduled to start w.e.f 01th January 2025 and 15th February 2025.

OFFICIAL SYLLABUS

Unit I: Electrostatics

Chapter 1: Electric Charges and Fields

Electric Charges; Conservation of charge, Coulomb’s law force between two point charges, forces between multiple charges; superposition principle and continuous charge distribution.

Electric field, electric field due to a point charge, electric field lines, electric dipole, electric field due to a dipole, torque on a dipole in a uniform electric field.

Electric flux, statement of Gauss’s theorem and its applications to find field due to infinitely long straight wire, uniformly charged infinite plane sheet and uniformly charged thin spherical shell (field inside and outside).

Chapter 2: Electrostatic Potential and Capacitance

Electric potential, potential difference, electric potential due to a point charge, a dipole and system of charges; equipotential surfaces, electrical potential energy of a system of two point charges and of electric dipole in an electrostatic field.

Conductors and insulators, free charges and bound charges inside a conductor. Dielectrics and electric polarization, capacitors and capacitance, a combination of capacitors in series and in parallel, the capacitance of a parallel plate capacitor with and without dielectric medium between the plates, energy stored in a capacitor.

Unit II: Current Electricity

Chapter 3: Current Electricity

Electric current, the flow of electric charges in a metallic conductor, drift velocity, mobility and their relation with electric current; Ohm’s law, electrical resistance, V-I characteristics (linear and non-linear), electrical energy and power, electrical resistivity and conductivity, Carbon resistors, colour code for carbon resistors; series and parallel combinations of resistors; temperature dependence of resistance.

The internal resistance of a cell, potential difference and emf of a cell, a combination of cells in series and in parallel, Kirchhoff’s laws and simple applications, Wheatstone bridge, metre bridge.

Potentiometer – principle and its applications to measure potential difference and for comparing EMF of two cells; measurement of internal resistance of a cell.

Unit III: Magnetic Effects of Current and Magnetism

Chapter 4: Moving Charges and Magnetism

Concept of the magnetic field, Oersted’s experiment.

Biot – Savart law and its application to the current carrying circular loop.

Ampere’s law and its applications to an infinitely long straight wire. Straight and toroidal solenoids (only qualitative treatment), force on a moving charge in uniform magnetic and electric fields, Cyclotron.

Force on a current-carrying conductor in a uniform magnetic field, the force between two parallel current-carrying conductors-definition of an ampere, torque experienced by a current loop in a uniform magnetic field; moving coil galvanometer-its current sensitivity and conversion to ammeter and voltmeter.

Chapter 5: Magnetism and Matter

Current loop as a magnetic dipole and its magnetic dipole moment, magnetic dipole moment of a revolving electron, magnetic field intensity due to a magnetic dipole (bar magnet) along its axis and perpendicular to its axis, torque on a magnetic dipole (bar magnet) in a uniform magnetic field; bar magnet as an equivalent solenoid, magnetic field lines; earth’s magnetic field and magnetic elements.

Para-, dia- and ferromagnetic substances, with examples. Electromagnets and factors affecting their strengths, permanent magnets.

Unit IV: Electromagnetic Induction and Alternating Currents

Chapter 6: Electromagnetic Induction

Electromagnetic induction; Faraday’s laws, induced EMF and current; Lenz’s Law, Eddy currents. Self and mutual induction.

Chapter 7: Alternating Current

Alternating currents, peak and RMS value of alternating current/voltage; reactance and impedance; LC oscillations (qualitative treatment only), LCR series circuit, resonance; power in AC circuits, power factor, wattless current. AC generator and transformer.

Unit V: Electromagnetic waves

Chapter 8: Electromagnetic Waves

The basic idea of displacement current, Electromagnetic waves, their characteristics, and their Transverse nature (qualitative ideas only). Electromagnetic spectrum (radio waves, microwaves, infrared, visible, ultraviolet, X-rays, gamma rays) including elementary facts about their uses.

Unit VI: Optics

Chapter 9: Ray Optics and Optical Instruments

Ray Optics: Reflection of light, spherical mirrors, mirror formula, refraction of light, total internal reflection and its applications, optical fibres, refraction at spherical surfaces, lenses, thin lens formula, lensmaker’s formula, magnification, power of a lens, a combination of thin lenses in contact, refraction of light through a prism.

Scattering of the light-blue colour of the sky and the reddish appearance of the sun at sunrise and sunset.

Optical instruments: Microscopes and astronomical telescopes (reflecting and refracting) and their magnifying powers.

Chapter 10: Wave Optics

Wave optics: Wavefront and Huygens principle, reflection and refraction of plane wave at a plane surface using wavefronts. Proof of laws of reflection and refraction using Huygens principle. Interference, Young’s double-slit experiment and expression for fringe width,  coherent sources and sustained interference of light, diffraction due to a single slit, width of central maximum, resolving power of microscope and astronomical telescope, Polarisation, plane polarised light, Brewster’s law, uses of plane polarised light and Polaroids.

Unit VII: Dual Nature of Radiation and Matter

Chapter 11: Dual Nature of Radiation and Matter

Dual nature of radiation, Photoelectric effect, Hertz and Lenard’s observations;

Einstein’s photoelectric equation-particle nature of light.

Experimental study of the photoelectric effect

Matter waves-wave nature of particles, de-Broglie relation, Davisson-Germer experiment (experimental details should be omitted; only conclusion should be explained).

Unit VIII:   Atoms and Nuclei

Chapter 12: Atoms

Alpha-particle scattering experiment; Rutherford’s model of atom; Bohr model, energy levels, hydrogen spectrum.

Chapter 13: Nuclei

Composition and size of nucleus, Radioactivity, alpha, beta and gamma particles/rays and their properties; radioactive decay law, half-life and mean life.

Mass-energy relation, mass defect; binding energy per nucleon and its variation with mass number; nuclear fission, nuclear fusion.

Unit IX: Electronic Devices

Chapter 14: Semiconductor Electronics: Materials, Devices and Simple Circuits

Energy bands in conductors, semiconductors and insulators (qualitative ideas only)

Semiconductor diode – I-V characteristics in forward and reverse bias, diode as a rectifier;

Special purpose p-n junction diodes: LED, photodiode, solar cell and Zener diode and their characteristics, Zener diode as a voltage regulator.

PRACTICALS

1. The record to be submitted by the students at the time of their annual examination has to include:

2. Record at least 12 Experiments [with 6 from each section], to be performed by the students.

3. Record at least 6 Activities [with 3 each from section A and section B], to be performed by the students.

4. The Report of the project to be carried out by the students.

Evaluation Scheme

Time Allowed: Three hours

Max. Marks: 30

SECTION – A

Experiments

1. To determine the resistivity of two / three wires by plotting a graph for potential difference versus current.

2. To find the resistance of a given wire / standard resistor using a metre bridge.

3. To verify the laws of combination (series) of resistances using a metre bridge. OR

To verify the laws of combination (parallel) of resistances using a metre bridge.

4. To compare the EMF of two given primary cells using the potentiometer.

5. To determine the internal resistance of a given primary cell using a potentiometer.

6. To determine the resistance of a galvanometer by the half-deflection method and to find its figure of merit.

7. To convert the given galvanometer (of known resistance and figure of merit) into a voltmeter of desired range and to verify the same. OR

To convert the given galvanometer (of known resistance and figure of merit) into an ammeter of desired range and to verify the same.

8. To find the frequency of AC mains with a sonometer.

Activities

1. To measure the resistance and impedance of an inductor with or without an iron core.

2. To measure resistance, voltage (AC/DC), and current (AC) and check the continuity of a given circuit using a multimeter.

3. To assemble a household circuit comprising three bulbs, three (on/off) switches, a fuse and a power source.

4. To assemble the components of a given electrical circuit.

5. To study the variation in potential drop with length of a wire for a steady current.

6. To draw the diagram of a given open circuit comprising at least a battery, resistor/rheostat, key, ammeter and voltmeter. Mark the components that are not connected in proper order and correct the circuit and also the circuit diagram.

SECTION – B

Experiments

1. To find the value of v for different values of u in the case of a concave mirror and to find the focal length.

2. To find the focal length of a convex mirror, using a convex lens.

3. To find the focal length of a convex lens by plotting graphs between u and v or between 1/u and 1/v.

4. To find the focal length of a concave lens, using a convex lens.

5. To determine the angle of minimum deviation for a given prism by plotting a graph between the angle of incidence and the angle of deviation.

6. To determine the refractive index of a glass slab using a travelling microscope.

7. To find the refractive index of a liquid by using the convex lens and plane mirror.

8. To draw the  I-V characteristic curve for a p-n junction diode in forward bias and reverse bias.

9. To draw the characteristic curve of a Zener diode and to determine its reverse breaks down voltage.

Activities

1. To identify a diode, an LED, a resistor and a capacitor from a mixed collection of such items.

2. Use of a multimeter to see the unidirectional flow of current in the case of a diode and an LED and check whether a given electronic component (e.g., diode) is in working order.

3. To study the effect of intensity of light (by varying distance of the source) on an LDR.

4. To observe refraction and lateral deviation of a beam of light incident obliquely on a glass slab.

5. To observe polarization of light using two Polaroids.

6. To observe the diffraction of light due to a thin slit.

7. To study the nature and size of the image formed by an (i) convex lens, and (ii) concave mirror, on a screen by using a candle and a screen (for different distances of the candle from the lens/mirror).

8. To obtain a lens combination with the specified focal length by using two lenses from the given set of lenses.

Prescribed Books:

1. Physics, Class XI, Part -I and II, Published by NCERT

2. Physics, Class XII, Part -I and II, Published by NCERT.

3. Laboratory Manual of Physics for class XII Published by NCERT.

4. The list of other related books and manuals brought out by NCERT (consider multimedia also).

TO KNOW MORE

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