NCERT Solutions
Class 12 Physics
14 chapters · 21 important questions
Electric Charges and Fields
Covers Coulomb's law, electric field, field lines, Gauss's law and its applications. Electric dipole in external field is a key derivation topic.
Key Topics
Important Questions
State and prove Gauss's law. Apply it to find the electric field due to an infinitely long straight wire.
Derive an expression for the electric field on the equatorial line of an electric dipole.
Electrostatic Potential and Capacitance
Covers electric potential, potential due to a dipole, equipotential surfaces, and capacitors. Energy stored in a capacitor and dielectrics are key numericals.
Key Topics
Important Questions
Derive the expression for the energy stored in a parallel plate capacitor. What happens when a dielectric slab is inserted?
Current Electricity
Covers Ohm's law, drift velocity, resistivity, Kirchhoff's laws, and Wheatstone bridge. The internal resistance of a cell and EMF are important numerical topics.
Key Topics
Important Questions
State Kirchhoff's laws. Using them, find the current in each branch of a given circuit.
Derive the condition for balance of a Wheatstone bridge.
Moving Charges and Magnetism
Covers force on a moving charge (Lorentz force), force on a current-carrying conductor, Biot-Savart law, Ampere's circuital law, and the moving coil galvanometer.
Key Topics
Important Questions
State Biot-Savart law. Use it to find the magnetic field at the centre of a circular current loop.
Magnetism and Matter
Covers bar magnets, earth's magnetism, and magnetic properties of materials (diamagnetic, paramagnetic, ferromagnetic). Hysteresis loop is an important concept.
Key Topics
Important Questions
Distinguish between diamagnetic, paramagnetic and ferromagnetic substances. Give one example of each.
Electromagnetic Induction
Covers Faraday's laws, Lenz's law, self and mutual inductance. Eddy currents and their applications are included.
Key Topics
Important Questions
State Faraday's laws of electromagnetic induction. Derive an expression for motional EMF.
Alternating Current
Covers AC circuits with R, L, C individually and in series. Resonance, power factor, and LC oscillations are key topics. Transformers are also covered.
Key Topics
Important Questions
Derive an expression for the impedance of a series LCR circuit. Define resonance and Q-factor.
An LCR circuit has L = 0.1H, C = 25μF, R = 10Ω. Find the resonant frequency.
Electromagnetic Waves
Covers the nature of electromagnetic waves, their transverse character, and the electromagnetic spectrum. Properties of EM waves and their uses are frequently asked.
Key Topics
Important Questions
What is displacement current? Why did Maxwell introduce it?
Describe the electromagnetic spectrum. Give one use of each type of radiation.
Ray Optics and Optical Instruments
Covers reflection and refraction, total internal reflection, lenses, and optical instruments (microscope, telescope). Lens maker's formula and power of a lens are key numericals.
Key Topics
Important Questions
Draw a ray diagram for a compound microscope when the final image is at infinity. Derive the expression for magnifying power.
Wave Optics
Covers Huygens' principle, interference (Young's double slit experiment), diffraction, and polarisation. YDSE calculations are common board numericals.
Key Topics
Important Questions
In Young's double slit experiment, derive the expression for fringe width. What happens to the fringe width if: (i) wavelength is increased (ii) slit separation is increased?
Dual Nature of Radiation and Matter
Covers photoelectric effect, Einstein's photoelectric equation, wave-particle duality, and de Broglie wavelength. Millikan's experiment verification is included.
Key Topics
Important Questions
Explain the photoelectric effect. Write Einstein's photoelectric equation and explain each term.
Calculate the de Broglie wavelength of an electron accelerated through 100V.
Atoms
Covers Rutherford's model, Bohr's atomic model, hydrogen spectrum, and energy levels. Bohr's postulates and the Rydberg formula are frequently asked.
Key Topics
Important Questions
State Bohr's postulates. Derive the expression for the radius of the nth orbit of hydrogen atom.
Nuclei
Covers nuclear mass, binding energy, radioactive decay, and nuclear reactions. Half-life calculations and nuclear fission and fusion are key topics.
Key Topics
Important Questions
What is binding energy? Draw a binding energy per nucleon vs mass number graph and explain its features.
The half life of a radioactive isotope is 5 years. How much of 100g remains after 20 years?
Semiconductor Electronics
Covers energy bands, types of semiconductors, p-n junction diode, rectifiers, and transistors. Logic gates (AND, OR, NOT, NAND, NOR) are included.
Key Topics
Important Questions
Explain the working of a p-n junction diode as a full wave rectifier with a circuit diagram and waveform.
Draw the truth table for NAND and NOR gates. Why are they called universal gates?