BIOLOGY MOST IMPORTANT TOPIC CLASS 12

CBSE Class 12 Physics : Important Topics and Tips for Finals

Students your final exams are just around the corner. Students are busy with their last minute revisions and trying to get the most out of their study hours these days.
 
But you do not need to panic as out the team of experts at Meritnation has come up with some great insights into each chapter for your Physics exam. These key revision points and quick tips will help you prepare intelligently for the exams. Even if you have left out certain chapters for last minute preparations or revisions, these tips will help you get through them better.
 
 

Chapter 1 – Electronic Charges and Field

Important Topics:

1. Coulomb’s Law
2. Forces between multiple charges electric field due to system of charges
3. Electric dipole’s electric field on axial and equatorial point
4. Electric dipole in external electric field
5. Gauss’s law applications
 

MERITNATION TIPS: a) The mention topics are based on basic Coulomb’s force and electric field due to charges. b) Numericals from applications of Gauss law, forces between system of charges and Electric field due to system of charges are asked very frequently. c) Tracing electric field lines for monopole, dipole or system of charges is a very interesting as well as important topic. d) Straight forward derivations are asked as Short Answers-II for torque experienced by dipoles, electric field due to dipole on both axial and equatorial points. e) It is also advised to make a small summary for results obtained by application of Gauss law for quick review.

 

Chapter 2 – Electrostatic Potential and Capacitance

Important Topics:

1. Potential due to electric dipole and system of charges 2. Electric potential energy due to electric dipole and system of charges
3. Equipotential surfaces
4. Effect of dielectric on capacitors
5. Combinations of capacitors
6. Energy stored in capacitors
 

MERITNATION TIPS: a) The unit provides a good weightage to the numericals and direct derivations, so it is advised that no topic should be skipped. b) Derivations or topics like energy stored in the capacitors, potential due to electric dipole and potential energy of system of charges are frequently asked. c) Both Short Answers and Long Answer numericals are asked to calculate the potential energy due to system of charges. d) Complex combinations of capacitors are given to evaluate the effective capacitance or charge on plates. Do intensive study of the topic. e) Tracing equipotential surface for dipole or system of charges is an important an interesting topic. very short questions are asked from this topic.

 

Chapter 3 – Current Electricity

Important Topics:

1. Ohm’s Law
2. Limitations of ohm’s law
3. Resistivity of different materials
4. Combination of resistors
5. Combination of cells
6. Kirchhoff’s law
7. Meter bridge
8. Potentiometer
 

MERITNATION TIPS: a) Definitions and relations of resistance, conductance, resistivity, conductivity, drift velocity, internal resistance, cell EMF are asked for short answers and very short answer very frequently. b) Graph for resistivity for metals, alloys and semiconductors should be practised. c) Interpretation of complex circuits involving resistors and cells should be resolved into simple parallel and series combination should be practised. Numericals involving these circuits are frequently asked and use of Wheatstone bridge and Kirchhoff’s law should be used wherever required. Student should practise a wide range of such problems to practise the topic. d) Direct questions are asked every year from the topics Meter bridge or Potentiometer. e) Learn resistivity chart for different color codes, short numerical can be asked.

 

Chapter 4 – Moving Charges and Magnetism

Important Topics:

1. Magnetic force on current carrying wire
2. Motion in a magnetic field
3. Velocity selector
4. Cyclotron
5. Magnetic field on axis of circular current carrying loop 6. Ampere’s circuital law
7. Force between two parallel current carrying wires
8. Torque on current carrying loop in magnetic field
9. Moving coil galvanometer
 

MERITNATION TIPS: a) Direct derivations from topics like Magnetic force on axis of circular coil, ampere circuital law, forces between two current carrying wires and torque on current carrying loop in magnetic field are asked. b) Numericals from mentioned topics are most of the time simple based on the above derived relations or on motion in magnetic field, torque on current carrying loop placed in magnetic field, velocity selector are asked. c) Cyclotron, with its working and figure should be studied intensively. The topics are not much complex but revising the concepts will help.

 

Chapter 5 – Magnetism and Matter

Important Topics:

1. Axial magnetic field of bar magnet as solenoid
2. Electric dipole in uniform magnetic field
3. Diamagnetic, Paramagnetic, Ferromagnetic Substances
4. Hysteresis Loop
 

MERITNATION TIPS: a) It is an easy topic and might not require intensive study but to solve numericals or short answers based on topic, inclination and dip, it is advised to thoroughly understand the topic. b) Interpretation of hysteresis loop is very helpful. Make a small comparison table for Diamagnetic, Paramagnetic, Ferromagnetic substances. c) Learn the topics like dipole in uniform magnetic field and bar magnet as solenoid, keep the analogy of electrostatics in mind. Electrostatics and magnetics analogy is very helpful while learning the topics of magnetics

 

Chapter 6 – Electromagnetic Induction

Important Topics:

1. Magnetic flux
2. Faraday’s law of induction
3. Lens law
4. Motional EMF
5. Self inductance and mutual inductance
 

MERITNATION TIPS: a) The chapter gives a good overview of electricity and magnetism together. The concept of emf induced in any conducting body on change in magnetic field should be very well understood. b) A variety of numericals are asked based on the same concept of emf induced. practise good number of problems for the same. c) Short answers from lens law are also important. d) While solving the numericals please keep in mind the direction of magnetic field or the induced emf. Avoid any such blunder.

 

Chapter 7 – Alternating Current

Important Topics:

1. RC, LC, LR and LCR Circuits
2. LC oscillations
3. Power factor
4. Resonance and Sharpness
5. Transformers
 

MERITNATION TIPS: a) Make a comparing summary for RC, LC, LR and LCR combinations with their impedances and phase diagrams and other key points. This is the best method to avoid confusion while derivation or solving numericals from the topic. b) Condition for resonance and sharpness of resonance is an important relation. Power factor and LC oscillations are asked as both theoretical questions and numericals. Intensively study LC oscillations, it is an important topic. c) Transformers numericals for short answers are asked sometimes.

 

Chapter 8 – Electromagnetic Waves

Important Topics:

1. Displacement Current
2. EM waves
3. Nature of em waves
 

MERITNATION TIPS: a) Short and simple numerical for short answers are asked from the topic. b) Numericals from displacement current are also important. Make a comparison table of all the types of waves in the topic and mark their range in the spectrum and their important properties and uses. This does not requires intensive study but the table will help in answering very short as well as short questions from the topic. c) Read about the nature of em waves.

 

Chapter 9 – Ray Optics and Optical Instruments

Important Topics:

1. Image formation by spherical mirrors
2. Image formation by spherical lenses
3. Total internal reflection
4. Power and combination of lenses
5. Refraction through a Prism
6. Natural phenomenons due to light
7. Eye
8. Telescope
9. Microscope
 

MERITNATION TIPS: a) All the mentioned important topics are easy, but often students are confused in mirror and lenses and do blunders due to wrong sign conventions. Strictly follow the new Cartesian sign conventions while using mirror or lens formula. it is also suggested to make a comparing table for both the mirrors and lenses to avoid confusion and memorising. b) Total internal reflection is an easy topic and should not be skipped. c) Power of lenses and combinations of lenses are important for numericals. Take care of unit of f while evaluating the power of lens in dioptre, as this is a very common mistake we do. d) Refraction through prism is an important topic, keep the derivation and important relations on tips. e) The topic on Eye does not require too much mug-up but you must study it and understand its basic structure and working. f) Telescope and microscope are both important optical instrument based on the above topics we have studies, so just derive the relations once and memorise the relations.

 

Chapter 10 – Wave optics

Important Topics:

1. Reflection and refraction of plane waves using Huygen principle
2. Incoherent and coherent waves addition
3. Interference and Young’s double slit experiment
4. Diffraction of light
5. Resolving power of optical Instruments
6. Polarisation by scattering
 

MERITNATION TIPS: a) Deduction of law of reflection and refraction is an important derivation using Huygens principle is often asked. b) Expression for fringe width in YDSE is important derivation. make a short summary for comparison of the widths of bright and dark fringes in YDSE. Expression for angular width of central maximum of diffraction pattern and brewster law are frequently asked. c) Apart from the theory and direct derivations from the above topics, numericals from mentioned important topics are also included in exams. Learn to trace the wavefronts for both reflection and refraction for the optical surface using Huygens theory. d) Polarisation does not need intensive study, only a brief understanding is enough to answer the basic questions asked.

 

Chapter 11 – Dual Nature of Radiation and Matter

Important Topics:

1. Photoelectric effect
2. Einstein photoelectric equation
3. de Broglie hypothesis
4. Davisson and Germer experiment
 

MERITNATION TIPS: a) List down the important relations based on the physical quantities like energy, momentum and power of photons, and relation of de Broglie’s hypothesis. As simple numericals based on the relations are asked often. while solving the numericals keep care of conversion of units. From eV to Joules, Planck’s and de Broglie hypothesis gives quality questions, so study both the theories briefly. b) Einstein’s photoelectric equation, Planck’s constant and work function of metal, de Broglie’s wavelength are important topics for direct derivations. Though short numericals are also included in the exams. c) Often a long question is asked from Davisson Germer experiment. d) Graphical interpretation of relation between intensity and photoelectric current and other mentioned important topics from experimental effect of photoelectric effect is asked frequently.

 

Chapter 12 – Atoms

Important Topics:

1. Electron Orbits
2. Atomic spectra
3. Bohr Model of Hydrogen atom
4. Line spectra of Hydrogen atom
5. de-Broglie explanation of Bohr’s postulate
 

MERITNATION TIPS: a) List up all the relations of Bohr model of hydrogen and atomic spectra. DIstance for closest approach is an important topic for derivation. Derive all the relations of Bohr’s theory of hydrogen atom. Rydberg formula is also an important relation. b) Revise the series once with relations from line spectra. c) Topics covered in this unit are easy but still important relations should be learned to do well in numericals.

 

Chapter 13 – Nuclei

Important Topics:

1. Nuclear binding energy
2. Radioactivity
3. Radioactive decays
 

MERITNATION TIPS: a) The chapter is basically divided in two sections the first section is completely theoretical. Deep understanding of the topic is required to understand the second section of the chapter. The second half of the chapter includes radioactivity, from which numericals and reaction based questions are asked. b) Interpretation of binding energy curve is also very important. c) For radioactivity, derivations for mean life, half life and decay constant are frequently asked. These relations are also important for solving short numericals from the same topic.

 

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

Important Topics:

1. Intrinsic semiconductors
2. Extrinsic semiconductors
3. p-n Junction diode
4. p-n Junction in forward bias and reverse bias
5. Junction diode as rectifier
6. Zener diode as voltage regulator
7. n-p-n and p-n-p transistor
8. Transistor as an amplifier
9. Logic gates
 

MERITNATION TIPS: a) Differentiate between intrinsic and extrinsic semiconductors and n-type and p type semiconductors. compare both the topics and study. Interpret the conductivity of different materials. b) Current in semiconductors, electrical resistivity of semiconductors are important relations for derivations. c) Graphical representation of voltage characteristics of zener diode is asked frequently. d) Long questions are asked from transistors as an oscillators, amplifiers, rectifiers. So be thorough with their derivations. e) Logic gate is an interesting topic, you can score easily by simple revising them once. Practise certain sets of the gate combinations and avoid intensive study. Distribute the time logically while preparing for the chapter. Use figure wherever required while answering the questions.

 

Chapter 15 – Communication Systems

Important Topics:

1. Elements of communication system
2. Basic terminologies of electronic communication system
3. Propagation of em waves
4. Amplitude modulation
 

MERITNATION TIPS: a) Block diagrams are very important. learn all the terminologies on tips, descriptive questions from wave propagations are asked directly in exams.b) Modulation is an important topic, practise the derivation and all the expressions. c) Expression for height of antenna is asked many times previously. Modulation factor and relation for amplitude modulated wave is also important. The topics are easy, quality and simple questions are asked so keep a brief review of overall theory.