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# CBSE Class 12 Physics Notes: Important Chapters CBSE Class 12 Physics Notes: Physics needs an in-depth understanding of the subject and formulas so that students can get well-versed with both theory and practical sections. The CBSE Physics Class 12 Notes provided in this article are aimed at helping students develop conceptual understanding of the important chapters. Students can easily understand the complicated topics as they have been clearly explained.

It is important for the students to prepare the notes as they help in last-minute revision. Going through the notes will cover important concepts in short. This helps students to carry out revision quickly and it also increases the scope of acquiring good marks. To make this process easy, we have gathered the CBSE Class 12 Physics notes for student’s reference. Keep reading to know more about the 12th Physics notes of the important chapters.

## CBSE Class 12 Physics Notes: Overview

Before, going into the details of Class 12 Physics notes, let us have an overview of all the chapters covered in the subject..

### CBSE Class 12 Physics Chapter 1 Notes : Electric Charges and Fields

• Electric Charge is the property associated with matter. It produces & experiences both electric and magnetic effect
• Conductors are the substances that allow the movement of electricity through them. Example: Metals
• Insulators are the substances that offer high resistance to the passage of electricity. Example: Plastic rod and nylon
• Frictional electricity is caused due to the transference of electrons
• If a system contains n charges like q1, q2, q3 and qn, the total charge of the system is q1+q2+……+qn
• The total charge of an isolated system is always conserved which is known as the conservation of charge
• Quantisation of charge exists in discrete amounts rather than continuous value and hence, quantised. Charge on an object is q=±ne. Here ‘n’ is an integer and ‘e’ is an electronic charge
• Coulomb’s Law states that the electrostatic force of interaction or repulsion acting between two stationary point charges is given by
• Electric Field Intensity: The force experienced per unit positive test charge placed at that point without disturbing the source charge.

### CBSE Class 12 Physics Chapter 2 Notes : Electrostatic Potential and Capacitance

• Electrostatic Potential is an electric field 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.
• Electrostatic Potential Difference is the difference of electrostatic potentials of the two points in the electric field
• When a positive charge is released into an electric field, it experiences a force that moves it from higher potential to lower potential. But, a negative charge experiences a force that moves it from lower potential to higher.
• Work implemented in moving a unit positive test charge over a closed path in an electric field is zero which is why electrostatic forces are conservative in nature.
• Potential energy of a dipole in a uniform electric field E is represented as Potential energy = -p.E
• Electrostatic shielding is the process involving the making of a region free from any electric field

### CBSE Class 12 Physics Notes: Chapter 3: Current Electricity

• Electric Current: The rate of flow of electric charge through any cross-section of a conductor. Current is a scalar quantity
• The current density at a point in a conductor is the ratio of the current at that point in the conductor to the area of cross-section of the conductor at that point provided the area is held normal to the direction of flow of current. It is a vector quantity
• When it comes to solids, all metals are good conductors of electricity and the cause of conductance is free electrons
• When an external electric field is applied, the average velocity with which the free electrons move towards the positive end of a conductor is known as the drift velocity
• The ratio of drift velocity of electrons and the applied electric field is known as mobility.
• Ohm’s Law states that when the temperature is constant, the potential difference V across the ends of a given metallic wire (conductor) in an circuit (electric) is directly proportional to the current. V=IR where R is the resistance
• Conductivity is the reciprocal of resistivity of a conductor. It is written as, σ = 1/ρ

### CBSE Class 12 Physics Notes: Chapter 4: Moving Charges and Magnetism

• Moving Charges and Magnetism – Magnetic field is the space of surroundings of a magnet or a current-carrying conductor in which its magnetic influence can be experienced
• Ampere’s Circuital Law states that the line integral of the magnetic field B around any closed loop is equal to μ0 times the total current I threading through the loop. It is represented as
• Magnetic field due to a straight solenoid: At any point inside the solenoid, B = μ0nI and n = number of turns per unit length
• At the ends of the solenoid, B = 1/2 μ0nI
• Magnetic field due to Toroidal Solenoid: (i) Inside the toroidal solenoid, B =μ0nI, here, n =N/2πr ,N= total number of turns

(ii) In the open space, interior or exterior of toroidal solenoid, B= 0

### CBSE Class 12 Physics Notes: Chapter 5: Magnetism and Matter

• Magnetism and Matter -The magnetic dipole moment of a magnetic dipole is represented as M = m × 2 (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 the South pole to North pole.
• Magnetic Field Lines are the imaginary lines that give pictorial representation for the magnetic field inside and around the magnet.
• Potential energy of a magnetic dipole in a magnetic field is represented by U = – MB cos θ = – M . B where, θ is the angle between M and B
• Current loop behaves like a magnetic dipole whose dipole moment is represented as M=IA
• Potential energy of a magnetic dipole in a magnetic field is represented by U = – MB cos θ = – M . B where, θ is the angle between M and B.

### CBSE Class 12 Physics Notes: Chapter 6: Electromagnetic Induction

• Magnetic Flux: The magnetic flux linked with any surface is equal to the total number of magnetic lines of force passing normally through it. It is a scalar quantity
• The phenomenon of generation of current or emf by changing the magnetic flux is known as Electromagnetic Induction (EMI)
• According to the Faraday’s Law of Electromagnetic Induction, first law states that when the magnetic flux linked with the closed loop or circuit changes, an emf is induced in the loop or circuit which lasts so long as change in flux continuous
• Second law of Faraday’s Law of Electromagnetic Induction states that the induced emf in a closed loop or circuit is directly proportional to the rate of change of magnetic flux linked with the closed loop or circuit
• The induced emf can be produced in a coil by (i) putting the coil/loop/circuit in a varying magnetic field, (ii) changing the area A of the coil inside the magnetic field and (iii) changing the angle 0 between B and A.

### CBSE Class 12 Physics Notes: Chapter 7: Alternating Current

• Alternating Current (AC) is the current that varies in both magnitude and direction alternatively and periodically
• Effective Value or rms Value of AC is defined as the value of AC over a complete cycle that would generate the same amount of heat in a given resistor that is generated by steady current in the same resistor and in the same time during a complete cycle.
• Capacitive Reactance (Xc) The opposing nature of capacitor to the flow of alternating current is called capacitive reactance. It is represented as
• Wattless Current is the current in an AC circuit when average power consumption in an AC circuit is zero. It is also known as idle current

### CBSE Class 12 Physics Notes: Chapter 8: Electromagnetic Waves

• Displacement current is the current that comes into play in the region in which the electric field and the electric flux is changing with time.
• 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.
• In an electromagnetic wave, two fields become the source of each other and the wave propagates in a direction perpendicular to both the fields. It is a wave radiated by an accelerated or oscillatory charge in which a varying magnetic field is the source of electric field and varying electric field is the source of magnetic field
• E (electric field) and B (magnetic field) in electromagnetic waves are in the same phase

### CBSE Class 12 Physics Notes: Chapter 9: Ray Optics and Optical Instruments

• Ray Optics and Optical Instruments – Reflection is the process of changing the path of light devoid of any change in the medium
• According to the first law of reflection, the angle of incidence i is equal to the angle of reflection r, which is given by ∠i = ∠r.
• According to the second law of reflection, the incident ray, reflected ray and normal to the reflecting surface at the point of incidence all lie in the same plane.
• Reflecting surface of a spherical mirror is a part of a hollow sphere. Spherical mirrors are of two types namely concave spherical mirror and convex spherical mirror.
• Magnification (m) is negative corresponding to real image and positive for virtual image
• A lens is a transparent medium bounded by two surfaces of which one or both surfaces are spherical.
• Convex lens is the lens which is thicker at the center and thinner at its end
• Concave lens is the lens which is thinner at the center and thicker at its end

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### FAQs on CBSE Class 12 Physics Notes

Below-mentioned are some of the frequently asked questions related to CBSE Class 12 Physics Notes

Q.1: What are conductors and Insulators?
Ans: Conductors are the substances that allow the movement of electricity through them. Example: Metals. Insulators are the substances that offer high resistance to the passage of electricity. Example: Plastic rod and nylon

Q.2: Where can I find CBSE Class 12 Physics notes?
Ans: Students can find the CBSE Class 12 Physics notes in this article from Embibe

Q.3: How many chapters are there in CBSE Class 12 Physics?
Ans: CBSE Class 12 Physics consists of 15 chapters

Q.4: What is an Electrostatic potential?
Ans: An Electrostatic potential is an electric field 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

Q.5: What is a magnetic field?
Ans:
A magnetic field is the space of surroundings of a magnet or a current-carrying conductor in which its magnetic influence can be experienced

Students can access the previous year papers from CBSE official website

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