# Important topics for Class 12 Physics Board Exam This is a special request post for all those out there who are preparing for Class 12 board Exams. If you want to score good marks in the upcoming Board Examinations though your marks so far has been not that good, then this post will help you.

# How will this post help in scoring good marks in Board Exam?

I have given a list of selected topics from which questions are asked almost every year and these questions cover nearly 60 % of the marks. So, if you concentrate on these topics and practise them well, then surely you can score upto 60% or more in the Board Exams.

There are TEN distinct units in Class 12 Physics. I have given here unit wise list of topics. You have to practise these topics from your text book to perfection

## ELECTROSTATICS

Coulomb’s Law (Statement, mathematical form, vector form and in terms of position vectors)

Properties of Electric field lines

Electric field at a point due to an electric dipole (Axial position and equatorial position)

State Gauss theorem, express it mathematically and apply it to determine the electric field at a point due to (a) a point charge (b) a line of charge and (c) due to a charged conducting spherical shell (inside the sphere, on the sphere and outside the sphere)

Equipotential surfaces and its properties

Principle of a parallel plate capacitor

Capacitance of a conducting sphere

Capacitance of a parallel plate capacitor (a) with no medium and (b) with a dielectric medium completely filling the space between the two plates.

Combinations of capacitors (series and parallel)

Capacitance of a parallel plate capacitor with a dielectric slad partially filling the space between the plates of a parallel plate capacitor.

## CURRENT ELECTRICITY

Drift velocity

Derive the expression I = nAev

Deduce Ohm’s law from elementary concepts

What are non ohmic conductors? Give example

Color coding of carbon resistors

Combination of resistors (Series and Parallel)

Kirchoff’s laws and applications

Wheatstone’s bridge principle, derive using Kirchoff’s laws

Metre Bridge and its applications

Principle of a potentiometer

Experiment to determine (a) the ratio of emfs of two primary cells and (b) the internal resistance of a primary cell

## MAGNETIC EFFECTS OF ELECTRIC CURRENT AND MAGNETISM

Biot Savart Law and applications (Magnetic field at a point (a) at the centre of a circular loop carrying current (b) at a point on the axis of a circular loop carrying current)

Ampere’s circuital law and applications (Magnetic field at a point due to (a) an infinitely long straight conductor carrying current (b) a current carrying solenoid and (c) a current carrying torroidal solenoid.

Magnetic elements of earth

Properties of magnetic materials – Diamagnetic, paramagnetic and ferromagnetic substance

## ELECTROMAGNETIC INDUCTION AND ALTERNATING CURRENT

Faraday’s laws of electromagnetic induction

State Lenz’s law and show that it is in accordance with law of conservation of energy

Eddy currents

Self induction, self inductance, unit

Self inductance of a solenoid

Mutual induction, mutual induction and its unit

mutual inductance of a pair of solenoids

Factors affecting mutual inductance

Mean value of AC

RMS value of AC

AC circuit containing (a) R only (b) C only (c) L only

Impedance of and LCR series circuit

Resonance in LCR circuit and derive expression for resonant frequency, Graph showing variation of amplitude of current with frequency in LCR circuit

Q factor of resonance

Average power in AC

Wattless current

Power factor in AC circuit

Principle construction and working of a transformer

Losses in  a transformer and how the losses are reduced

## ELECTROMAGNETIC WAVES

Displacement current

Inadequacy of Ampere’s circuital law

Modified Ampere’s circuital law (Ampere Maxwell rule)

Maxwell’s equations

Electromagnetic spectrum

Properties of electromagnetic waves

Atleast two uses of each EM wave

## OPTICS

Refraction through a glass slab and expression for lateral displacement

Refraction through a glass prism and expression for refractive index of the material of the prism

Refraction at a spherical surface

Refraction through a lens and lens maker’s formula

Thin lens formula

Effective focal length of two thin lenses in contact

Power of a lens and a combination of lenses

Total internal reflection, critical angle

Total reflecting prisms and applications

Optical fibres

Ray diagram showing image formation by a Simple microscope and its magnifying power

Ray diagram showing image formation by a compound microscope and its magnifying power

Ray diagram showing image formation by an astronomical telescope and its magnifying power (in normal adjustment and when the image is formed at the least distance of distinct vision)

#### WAVE OPTICS

Huygen’s wave theory and postulates of secondary wavelets

Prove the laws of reflection using Huygen’s theory of secondary wavelets

Prove the laws of refraction using Huygen’s theory of secondary wavelets

Principle of superposition of waves and condition for maxima and minima due to superposition (Theory of interference)

Experimental arrangement for Young’s double slit experiment and observations on screen

Derive an expression for fringe width in Young;s double slit experiment

Show that both bright fringe and dark fringe are of equal width in YDSE

Draw a graph showing the variation of intensity of light with distance from the centre of fringe pattern in young’s double slit experiment

Draw the experimental arrangement for diffraction at single slit

Deduce the condition for dark fringe and bright fringe in diffraction at a single slit

Malus’ law

Brewster’s law

Polaroids and their applications

Scattering of light

Why sky is blue?

Why sun appears reddish during sunrise and sunset?

## DUAL NATURE OF MATTER AND RADIATIONS

Laws of Photoelectric effect, experimental setup and observations with graphs

Einstein’s photoelectric effect and explanation of the laws of photoelectric effect using the equation

De Broglie’s hypothesis, equation and its explanation

Davisson Germer experiment (Experimental evidence for wave nature of matter)

## ATOMIC AND NUCLEAR PHYSICS

Rutherford’s experiment and conclusions about structure of atom

Distance of closest approach

Show that nuclear density is independent of mass number

Postulates of Bohr atom model

Derivation for (a)orbital radius (b) speed of electron

Hydrogen spectrum

Rydberg formula

Binding energy of nucleus

Binding energy curve and explanation of release of energy during nuclear fission and fusion

## SEMICONDUCTOR DEVICES

VI characteristics of a diode

Diode as a rectifier (Half wave and full wave. Circuit diagram, working, input wave form, output wave form)

Zener diode characteristics

Zener diode as voltage regulator

Transistor action (How does a transistor conduct?)

CE Transistor Characteristics

Transistor as an amplifier in CE configuration

Transistor as an oscillator

LOGIC GATES (full topic to be learnt very well)

## COMMUNICATION SYSTEMS

Need for modulation (Height of antenna, effective power radiated, mixing up of signals)

All block diagrams given in text book with proper labeling

Height of antenna and range of transmission

Different modes of communication and corresponding range

Surface wave, Sky wave propagation, space wave propagation

Role of ionosphere in Sky wave

Amplitude modulation (Theory and diagram of circuitry and waveforms showing signal, carrier wave and modulated carrier wave)

Demodulation