CONCEPT LOGIC FOR CLASS 12TH
Key Concepts with Accurate Logic Technique FEATURES 3000+ Chapterwise Key Concept with Accurate Logic
Completely NCERT Based Clear your Concepts with Accurate Logic Strengthen Your Preparations
5 Model Test Papers Based on AIIMS
Class-XII Altis Vortex Delhi
EDITION : 2022 ISBN : 978-93-92761-32-4 BOOK CODE : 1161 Price : Rs. 475/-
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Directions: For Concept Building Approach/ How to Read Concepts and their Logic. Step 1: Hide the ″NCERT Logic″ (Right Side Column) of the page. Step 2: Read the ″NCERT Concept″ (Left Side Column) and try to give the explanation yourself with the theory you have studied. Step 3: Check your answer by uncovering the ″NCERT Logic″ (Right Side Column) Step 4: ″NCERT Logic″ (Right Side Column) is the perfect explanation for the ″NCERT Concept″ (Left Side Column).
Before reading every chapter in this book, make sure you have tried to atleast read the NCERT chapter once. This will help you to memorise the crude data directly given in our book
Important concepts from NCERT is given in the form of NCERT Concept and NCERT Logic so that it will help you while solving Problems in exams
First and foremost condition to solve any question is that you should know the correct NCERT logic behind concept mentioned in NCERT and we are bringing out the extract of all concepts with their perfect NCERT logic
All sentences in NCERT with words like "because". "therefore", "since", "due to", etc., have also been added in this book so that it will be helpful for your last minute revision
Most of the conceptual questions, A&R type questions, Match the column and statement based questions are prepared from line by line important points from NCERT
NCERT physics is given least importance by students and not well covered in many schools too and unfortunately almost all statements based questions or concept based questions is directly taken from NCERT Physics. We have tried to reduce the burden of students from NCERT physics by taking the essence of all chapters and important NCERT concepts which are expected to be asked in the upcoming examinations
This book will also help you to solve conceptual questions, statement based, assertion and reason type and match the column type questions in Chemistry and Physics
High order thinking skill questions expected in Biology section is also given due importance in every chapter in this book
Physics Ch. No.
Electric Charges and Fields
Electrostatic Potential and capacitance
Moving Charges and Magnetism
Magnetism and Matter
Ray optics and Optical Instruments
Dual Nature of Radiation and Matter
Atoms and Nuclei
Chemistry Ch. No.
The Solid State
General Principles and Process of Isolation of Elements
The p-Block Elements
The d & f-Blocks Elements
Haloalkanes and Haloarenes
Alcohol, Phenol & Ether
Aldehydes, Ketones and Carboxylic Acid
Chemistry in Everyday Life
Biology Ch. No.
Reproduction in Organisms
Sexual Reproduction in Flowering Plants
Principles of Inheritance and Variation
Molecular Basis of Inheritance
Human Health and Disease
Strategies for Enhancement in Food Production
Microbes in Human Welfare
Biotechnology: Principles and Processes
Biotechnology and its Applications
Organisms and Populations
Biodiversity and Conservation
Electric Charges and Fields
NOTE: Use these directions for each and every upcoming chapters. Step 1: Hide the ″NCERT Logic″ (Right Side Column) of the page. Step 2: Read the “NCERT Concept” (Left Side Column) and try to give the explanation yourself with the theory you have studied. Step 3: Check your answer by uncovering the ″NCERT Logic″ (Right Side Column) Step 4: ″NCERT Logic″ (Right Side Column) is the perfect explanation for the ″NCERT Concept″ (Left Side Column).
C : There is a spark or crackle when we take off our synthetic clothes or sweater in dry whether.
L : Discharge of electric charges through our body, which get accumulated due to rubbing of insulating surface cause spark.
C : It is observed that if two glass rods rubbed with wool or silk cloth are brought close to each other, they repel each other.
L : Electrification causes repulsion of polarity.
C : A compass needle is deflected by passing an electric current through a wire placed near the needle.
L : Electric charge in motion produce magnetic field .
C : On rubbing two body, the mass of one body slightly get lowered.
L : Loosely bounded electrons in a material are transferred on rubbing.
C : An ebonite rod held in hand can be charged by rubbing with funnel but a copper rod cannot be charged like this.
L : Ebonite is bad conductor of electricity,the charges so produced stay on ebonite rod.
C : When charge body is in contact with earth, all excess charge disappears.
L : A momentarily current passes to ground due to earthing.
C : During electrical connection in a home , a thick metal plate is buried deep into the earth and thick wires are drawn from this plate.
L : Excess charge leaks to earth .
Electric Charges and Fields 2
C : When we touch a pith ball with an electrified plastic rod, some of the negative charges on rod are transferred.
L : It is due to Charging by induction.
C : Electrostatic field lines do not form any closed loops.
L : Isolated positive and negative charge do exist.
C : Two field lines never cross each other.
L : At point of interaction field line will not have unique direction.
C : One can ignore quantization of electric charge when dealing with macroscopic scale.
L : The charge seems to varying in continuous manner when electrons are added or removed from body due to small mass.
C : At microscopic level, charge distribution is discontinuous.
L : At microscopic level charge distribution is discrete and separated by intervening space where there is no charge.
C : Total charge of an isolated system is conserved.
L : There is no creation or destruction of charge.
C : Electric field strength due point charge is larger than electric dipole.
L : For point charge electric field is inversely proportional to square of distance between charges while for electric dipole field strength depends upon inversely proportional to cube of distance.
C : Electric charge is scalar quantity.
L : It does not obey vector rules.
C : The test charge used to measure electric field at point is taken as unit in magnitude or very small.
L : It will produce its own electric field and measured value will be different from the actual.
C : Electric field intensity within a conductor is always zero.
L : Electric field lines of force cannot pass through the conductor.
C : During lightening ,it is safe to be sit inside the car.
L : The hollow structure of car provides electrostatic shielding
C : All the charges from a conductor to insulated conductor can be transferred.
L : It follows Principle of Van de Graff generator.
C : Electric field lines don't form closed loops.
L : No electric field lines exist inside the charged body.
C : Electrostatic experiments do not work during humid days.
L : Amount of water present in atmosphere makes air conducting. So the non conducting parts of instrument becomes conducting.
C : Water has a much greater dielectric constant than mica.
L : Water molecule has a permanent dipole moment.
Physics-XII L : No electric field line exist inside the charged body. or Electric filed lines do not originate or terminate on same charge
C : Electrostatic field at the surface of a charged conductor be perpendicular to every point on it.
L : The electric lines of forces exert lateral pressure on each other leads to repulsion b/w like charges.
C : Electrostatic potential is constant throughout the volume of the conductor and has the same value as on its surface.
L: E = −
C : Electric field discontinuous across the surface of a charged conductor. The electric potential also not discontinuous there.
L : Potential is continuous because if it is discontinuous the free charges will move from higher to lower potential to equalize the potential.
C : Ordinary rubber is an insulator but the special rubber tyres of aircrafts are made slightly conducting.
L : On account of friction b/w tyres and the runway, to leak the charge to earth, rubber tyres are made slightly conducting.
C : Vehicle carrying inflammable materials usually have metallic ropes touching the ground during motion.
L : The charge accumulated on the body may cause fire, metallic ropes ground these charges.
C : An electrostatic field line cannot be discontinuous.
L : An electrostatic field line is the path of a positively charged particles in an electric field.
C : A positively charged particle is free to move in an electric field along the line of force.
L : If charged particles in initially at rest, it will necessarily move along the line of force.
C : Electrostatic experiment do not work during humid days.
L : Humidity is the amount of water vapor present in atmosphere humidity makes the air conductive.
C : Electric potential rise or fall along an electric line of force.
L : The electric potential falls along a line of force because a line of force is always directed from higher to lower potential.
C : Electric potential at a point be zero, while the electric field is not zero.
L : Electric potential is zero at all points on equatorial line of electric dipole, while electric field strength is not zero.
C : On charging the curtain rod by touching the ball end and aluminium foil with an electrified body, they repel each other.
L : Charge is transferred to the curtain rod and the attached aluminium foil. Both the halves of the foil get similar charge.
C : The total charge of the electric dipole is obviously zero. This does not mean that the field of the electric dipole is zero.
L : At distances much larger than the separation of the two charges forming a dipole (r >> 2a), the fields due to q and –q nearly cancel out.
∆V ; E = 0 ⇔ ∆V = constant. r
Electric Charges and Fields
C : Electrostatic field line not form closed loops.
Electric Charges and Fields 4
C : Water molecules, H2O is polar molecules.
L : The centres of negative charges and of positive charges do not coincide. Therefore they have a permanent electric dipole moment, even in the absence of an electric field.
C : Consider The unit vector normal to surface 1 is in –x direction while the unit vector normal to surface 2 is in the +x direction. The net flux through the Gaussian surface is 2 EA. The charge enclosed by the closed surface is σA
L : Therefore, flux E.ΔS through both the surfaces are equal and add up
C : At the macroscopic level, the quantisation of charge has no practical consequence and can be ignored
L : One deals with charges that are enormous compared to the magnitude of charge e.
C : At the microscopic level, charge distribution is discontinuous,
L : They are discrete charges separated by intervening space where there is no charge.
C : You might wonder why the protons, all carrying positive charges, are compactly residing inside the nucleus. they do not fly away.
L : Third kind of a fundamental force, called the strong force which holds them together.
C : The electrons are not allowed to sit on top of the protons, i.e. inside the nucleus.
L : Due to the laws of quantum mechanics
C : Despite gravity being a much weaker force than electrostatic, can be a dominating and more pervasive force in nature.
L : Gravitational force has only one sign (always attractive), while Coulomb force can be of both signs (attractive and repulsive), allowing possibility of cancellation of electric forces
C : Charge is a scalar, Therefore the additive property of charge is not an ‘obvious’ property
L : Electric charge has no direction associated with it
C : Charge is not only a scalar (or invariant) under rotation; it is also invariant for frames of reference in relative motion. This is not always true for every scalar.
L : Kinetic energy is a scalar under rotation, but is not invariant for frames of reference in relative motion.
C : A quantity may be scalar but not conserved (like kinetic energy in an inelastic collision). On the other hand, one can have conserved vector quantity (e.g., angular momentum of an isolated system).
L : Conservation refers to invariance in time in a given frame of reference.
Electrostatic Potential and Capacitance
NOTE: Read the directions carefully given at the starting of the book before attempting.
C : When a dielectric is introduced and Battery is connected to capacitor, the capacity of capacitor increases.
L : Capacity of capacitor becomes K times i.e (dielectric constant) of initial capacitance.
C : A parallel plate of capacitor of capacitance C is charged to a potential difference V. The battery is disconnected and then dielectric slab is inserted between it. Its potential energy decreases.
L : Although its capacitance increases yet potential decreases 1/K times.
C : In the absence of an externally applied electric field, displacement per unit volume of polar dielectric material is always zero.
L : In polar dielectrics, each molecule has permanent dipole moment but these molecular dipoles are randomly oriented in the absence of an externally applied electric field.
C : When the space between the metallic plate is completely filled with conducting slab the capacitance of parallel plate capacitor becomes infinite.
L : Electric field inside a conductor is zero, results potential difference of two plate becomes zero.
C : Coulomb’s law follow inverse square law of force.
L : Electrostatic force between two static charges is inversely proportional to square of distance between them.
C : Gravitational as well as coulomb’s force are central force.
L : It acts along the line joining two charges or bodies.
C : Potential difference between shells depends on charge of inner shell.
L : Potential due to charge of outer shell remains same at every point inside the sphere.
C : Potential energy would not be meaningful if the work depended on the path.
L : Force can be defined as the negative of vector gradient of the potential field.
C : In the field of positive charge, the potential difference between potential near the charge and away from it is positive.
L : Potential is inversely proportional to the distance.
Electrostatic Potential and Capacitance 6
C : An equipotential surface is a surface with a constant value of potential at all points on the surface.
L : Electric field is normal at every point of the equipotential surface and distance is constant.
C : Inside a conductor, electrostatic field is zero and flux is zero.
L : In conductor free electrons resides on its surface.
C : Electric field inside a dielectric decreases ,when it is placed in an external electric field.
L : When a dielectric is placed in an external electric field the electric field due to polarization of the dielectric opposes it.
C : A comb run through one’s dry hair attracts small bits of paper.
L : Combs gets charged by friction and molecules in the paper gets polarised by the charged comb.
C : Special rubber tyres of aircraft are made slightly conducting.
L : Too much of static electricity accumulated may result in spark and result fire that’s why tyres of aircraft makes slightly conducting.
C : Vehicles containing inflammable materials usually have metallic ropes touching the ground during motion.
L : Charge produced by friction causes fire so, metallic ropes touching the ground for discharging for the safety of vehicles.
C : A bird perches on a bare high power line, nothing happens to the bird while a man gets shock.
L : Current passes only when there is difference in potential.
C : Dielectrics are non-conducting substance
L : In a dielectric free movement of charge is not possible.
C : Non-polar molecule has no permanent dipole moment.
L : In non polar molecule centre of positive and negative charges coincide so, net resultant is zero.
C : Polar molecules has permanent dipole.
L : Centre of positive and negative are separated even if there is no external field.
C : Dielectrics are also known as linear isotropic dielectrics.
L : The induced dipole moment is in the direction of the field and is proportional to the field strength.
C : If the charge on the capacitor is doubled, the electric field will also be doubled at every point.
L : Electric field is directly proportional to the charge on the capacitor.
C : Work done by an external force in bringing a unit charge from a point R to P is VP ─ VR i.e. difference of final and initial potential.
L : Electrostatic force is conservative force Fext = −FE
C : Potential due to a charge q at its own location is not defined.
L : It is infinite.
C : When dielectric slab of dielectric constant K is introduced between the plate, energy stored in the capacitor decreases.
L : Potential difference between two plate decrease by factor K, so energy also decreases.
Physics-XII C : When a charge q is placed at one of the eight corners of a cube, the flux coming out of a cube through all six faces is ϕ = qin/8ε0
1 part of charge is present at a corner if we 8
assume atom to be perfect sphere.
L : No work is done in moving the test charge from one point of equipotential surface to the other.
C : A hollow metal sphere of radius 5 cm is charged such that potential on its surface is 10 V. The potential at the center is also 10 V.
L : Electric potential at every point inside the charge spherical shell is same and equal to the electric potential on its surface.
C : A man in an insulated metallic cage does not receive a shock, even if the cage is connected to high voltage source.
L : The whole charge reside at the outer surface of hollow conductor.
C : An electrostatic field line is a continuous curve.
L : As Q0→ 0 ; A moving charge experiences a continuous force in electrostatic field.
C : Potential is constant inside the shell (as no work is done in moving a charge inside the shell), and, therefore, equals its value at the surface.
L : The electric field inside the shell is zero.
C : A comb run through one’s dry hair attracts small bits of paper
L : The comb gets charged by friction
Electrostatic Potential and Capacitance
C : For any charge configuration, equipotential surface through a point is normal to the electric field.
How To Use This Book Ÿ Ÿ Ÿ
Ÿ Ÿ Ÿ
Before reading every chapter in this book, make sure you have tried to atleast read the NCERT chapter once. This will help you to memorise the crude data directly given in our book Important concepts from NCERT is given in the form of NCERT Concept and NCERT Logic so that it will help you while solving Problems in exams First and foremost condition to solve any question is that you should know the correct NCERT logic behind concept mentioned in NCERT and we are bringing out the extract of all concepts with their perfect NCERT logic All sentences in NCERT with words like "because". "therefore", "since", "due to", etc., have also been added in this book so that it will be helpful for your last minute revision Most of the conceptual questions, A&R type questions, Match the column and statement based questions are prepared from line by line important points from NCERT NCERT physics is given least importance by students and not well covered in many schools too and unfortunately almost all statements based questions or concept based questions is directly taken from NCERT Physics. We have tried to reduce the burden of students from NCERT physics by taking the essence of all chapters and important NCERT concepts which are expected to be asked in the upcoming examinations This book will also help you to solve conceptual questions, statement based, assertion and reason type and match the column type questions in Chemistry and Physics High order thinking skill questions expected in Biology section is also given due importance in every chapter in this book
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