1. Metals They possess very low resistivity or high conductivity. ρ ~ 10-2.10-8 Ωm, σ ~102. 108 Sm-1 2. Semiconductors They have resistivity or conductivity intermediate to metals and insulators. ρ ~ 10-5. 106 Ωm, σ ~ 10+5 .10-6 Sm-1 Types of Semiconductors Types of semiconductors are given below: (i) Elements Semiconductors These semiconductors are available in natural form, e.g. silicon and germanium. […]

# CBSE Class 12 Sample Papers, Syllabus, Test Papers & NCERT Solutions

## Nuclei Class 12 Chapter 13 Notes

1. In every atom, the positive charge and mass are densely concentrated at the centre of the atom forming its nucleus. More than 99.9% mass of the atom is concentrated in the nucleus. 2. Atomic Mass Unit (amu) The unit to express atomic masses is called atomic mass unit. Atomic mass unit is defined as 1/12 th […]

## Atoms Class 12 Chapter 12 Notes

1. All elements consists of very small invisible particles, called atom. Every atom is a sphere of radius of the order of 10-10 m, in which entire mass is uniformly distributed and negative charged electrons revolve around the nucleus. 2. Experimental arrangement for α-scattering experiment and trajectory followed by α -particles 3. Impact parameter perpendicular distance of the velocity […]

## Dual Nature of Radiation and Matter Class 12 Chapter 11 Notes

1. Photoelectric Effect The phenomenon of emission of photoelectron from the surface of metal, when a light beam of suitable frequency is incident on it, is called photoelectric effect. The emitted electrons are called photoelectrons and the current so produced is called photoelectric current. Hertz’ Observation The phenomenon of photo electric emission was discovered in 1887 by […]

## Wave Optics Class 12 Chapter 10 Notes

1. Wave Optics Describes the connection between waves and rays of light. According to wave theory of light, light is a form of energy which travels through a medium in the form of transverse wave. 2. Wave front The locus of all those particles which are vibrating in the same phase at any instant is called wave […]

## Ray Optics and Optical Instruments Class 12 Chapter 9 Notes

1. Ray Optics or Geometrical Optics In this optics, the light is considered as a ray which travels in a straight line. It states that for each and every object, there is an image. 2. Reflection Reflection is the phenomenon of changing the path of light without any change in the medium. 3. Reflection of Light The returning […]

## Electromagnetic Waves Class 12 Chapter 8 Notes

1. Displacement Current The current which comes into play m the region in which the electric field and the electric flux is changing with time. It is given by 2. Need for Displacement Current Ampere’s circuital law for conduction current during charging of a capacitor was found inconsistent. Therefore, Maxwell modified Ampere’s circuital law. 3. The displacement current […]

## Alternating Current Class 12 Chapter 7 Notes

1. Alternating Current (AC) It is the current which varies in both magnitude as well as direction alternatively and periodically. I = I0 sin ωt or I = I0 cosωt where, I0 = peak value or maximum value of AC. 2. Effective Value or rms Value of AC It is defined as the value of AC over a complete cycle […]

## Electromagnetic Induction Class 12 Chapter 6 Notes

1. Magnetic Flux The magnetic flux linked with any surface is equal to total number of magnetic lines of force passing normally through it. It is a scalar quantity. 2. The phenomenon of generation of current or emf by changing the magnetic flux is known as Electromagnetic Induction EMI). 3. Faraday’s Law of Electromagnetic Induction First Law Whenever […]

## Magnetism And Matter Class 12 Chapter 5 Notes

1. The magnetic dipole moment of a magnetic dipole is given by M = m × 2I where, m is pole strength and 2I is dipole length directed from S to N. The SI unit of magnetic dipole moment is A-m2 or J/T. It is a vector quantity and its direction is from South pole to North […]

## Moving Charges and Magnetism Class 12 Chapter 4 Notes

1. The space in the surroundings of a magnet or a current-carrying conductor in which its magnetic influence can be experienced is called magnetic field. Its SI unit is Tesla (T). 2. Oersted experimentally demonstrated that the current-carrying conductor produces magnetic field around it. When key K is closed, then deflection occurs in the compass needle and […]

## Current Electricity Class 12 Chapter 3 Notes

1. The directed rate of flow of electric charge through any cross-section of a conductor is known as electric current. If ∆Q charge flows in time ∆t, then current at any time t is NOTE: Current is a scalar quantity. I is in the direction of flow of positive charge and opposite to the direction of flow […]

## Electrostatic Potential and Capacitance Class 12 Chapter 2 Notes

1. Electrostatic Potential The electrostatic potential at any point in an electric field is equal to the amount of work done per unit positive test charge or in bringing the unit positive test charge from infinite to that point, against the electrostatic force without acceleration. NOTE: Electrostatic potential is a state dependent function as electrostatic forces are […]

## Electric Charges and Fields Class 12 Chapter 1 Notes

1. Electric Charge Charge is the property associated with matter due to which it produces and experiences electric and magnetic effect. 2. Conductors and Insulators Those substances which readily allow the passage of electricity through them are called conductors, e.g. metals, the earth and those substances which offer high resistance to the passage of electricity are called […]

## Maths Notes for Class 12 – All Chapters

Chapter 1 Relations and Functions Class 12 Notes Chapter 2 Inverse Trigonometric Functions Class 12 Notes Chapter 3 Matrices Class 12 Notes Chapter 4 Determinants Class 12 Notes Chapter 5 Continuity and Differentiability Class 12 Notes Chapter 6 Application of Derivatives Class 12 Notes Chapter 7 Integrals Class 12 Notes Chapter 9 Differential Equations Class 12 Notes Chapter 10 Vector Algebra Class 12 Notes […]

## CBSE Class 12 Maths Chapter 13 Probability Notes

Event: A subset of the sample space associated with a random experiment is called an event or a case. e.g. In tossing a coin, getting either head or tail is an event. Equally Likely Events: The given events are said to be equally likely if none of them is expected to occur in preference to the other. […]

## CBSE Class 12 Maths Chapter 12 Linear Programming Notes

Linear Programming Problem: A linear programming problem is one in which we have to find optimal value (maximum or minimum) of a linear function of several variables (called objective function) subject to certain conditions that the variables are non-negative and satisfying by a set of linear inequalities with variables, are sometimes called division variables. Terms related […]

## CBSE Class 12 Maths Chapter 11 Three Dimensional Geometry Notes

Direction Cosines of a Line: If the directed line OP makes angles α, β, and γ with positive X-axis, Y-axis and Z-axis respectively, then cos α, cos β, and cos γ, are called direction cosines of a line. They are denoted by l, m, and n. Therefore, l = cos α, m = cos β and […]