NCERT Solutions and Notes for CBSE Class 12 Physics

CBSE Class 12 Physics Syllabus 2020-21

Time: 3 hrs. Max Marks: 70

Unit I: Electrostatics (23 Periods)

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 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

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 polarisation, capacitors and capacitance, combination of capacitors in series and in parallel, capacitance of a parallel plate capacitor with and without dielectric medium between the plates, energy stored in a capacitor.

Unit II: Current Electricity (15 Periods)

Chapter–3: Current Electricity

Electric  current, 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 nonlinear), electrical energy and power, electrical resistivity and conductivity; temperature dependence of resistance.

Internal resistance of a cell, potential difference and emf of a cell, combination of cells in series and in parallel, Kirchhoff’s laws and simple applications, Wheatstone bridge, metre bridge(qualitative ideas only)

Potentiometer  – principle  and its  applications  to measure potential  difference  and for comparing EMF of two cells; measurement of internal resistance of a cell(qualitative ideas only)

Unit III: Magnetic Effects of Current and Magnetism (16 Periods)

Chapter–4: Moving Charges and Magnetism

Concept of magnetic field, Oersted’s experiment.

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

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

Force on a current-carrying conductor in a uniform magnetic field, force between two parallel  current-carrying  conductors-definition  of  ampere,  torque experienced  by  a current loop  in 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, bar magnet as an equivalent solenoid, magnetic field lines; earth’s magnetic field and magnetic elements.

Unit IV: Electromagnetic Induction and Alternating Currents (19 Periods)

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

AC generator and transformer.

Unit V: Electromagnetic waves (2 Periods)

Chapter–8: Electromagnetic Waves

Electromagnetic waves, their characteristics, 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 (18 Periods)

Chapter–9: Ray Optics and Optical Instruments

Ray Optics: 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, combination of thin lenses in contact, refraction of light through a prism.

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 waves at a plane surface using wave fronts. 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

Unit VII: Dual Nature of Radiation and Matter (7 Periods)

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 photoelectric effect

Matter waves-wave nature of particles, de-Broglie relation

Unit VIII:  Atoms and Nuclei (11 Periods)

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 Nuclear force

Mass-energy relation, mass defect, nuclear fission, nuclear fusion.

Unit IX: Electronic Devices  (7 Periods)

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.

PRACTICALS [Total Periods: 32]

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

Record of at least 8 Experiments [with 4 from each section], to be performed by the students.

Record of at least  6 Activities  [with  3 each from section  A and section  B], to be demonstrated by teacher

Evaluation Scheme

Time Allowed: Three hours, Max. Marks: 30

SECTION–A Experiments

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

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

OR

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.

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

OR

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

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

5. 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.

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

Activities

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

2. To measure resistance, voltage (AC/DC), current (AC) and check 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.

Experiments

SECTION-B

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

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

OR

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

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

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

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

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

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 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 diffraction of light due to a thin slit.

7. To study the nature and size of the image formed by a (i) convex lens, (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.