CBSE Class 12 Physics Syllabus

Physics syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Physics in CBSE Class 12, not a summary of it.

1. 1

   Electric Charges and Fields

   7 topics

   • Electric Charges
   • Conservation of charge
   • Coulomb's law
   • Electric field
   • Electric field lines
   • Electric flux
   • Gauss's law
2. 2

   Electrostatic Potential and Capacitance

   7 topics

   • Electrostatic Potential
   • Potential due to a point charge
   • Equipotential surfaces
   • Electrical potential energy
   • Capacitors and capacitance
   • Combination of capacitors
   • Energy stored in a capacitor
3. 3

   Current Electricity

   7 topics

   • Electric current
   • Electric currents in conductors
   • Ohm's law
   • Drift of electrons and the origin of resistivity
   • Mobility
   • Resistivity of various materials
   • Temperature dependence of resistance

Physics flashcards for CBSE Class 12

24 of 50 cards from the Physics deck — real questions with worked answers.

1. What is electric charge, and what are its two types?

   Electric charge is a fundamental property of matter that causes it to experience a force in an electric field. The two types are positive charge (e.g., on a proton) and negative charge (e.g., on an electron). Like charges repel and unlike charges attract.

2. State the law of conservation of charge.

   The total electric charge of an isolated system remains constant; charge can neither be created nor destroyed, only transferred from one body to another.

3. What does it mean that charge is quantized? Give the formula.

   Charge exists only in integral multiples of the elementary charge e. Q = ne, where n is an integer and e = 1.6 x 10^-19 C.

4. What is the additive property of electric charge?

   The total charge of a system is the algebraic sum (taking signs into account) of all individual charges present in the system.

5. State Coulomb's law and give its formula.

   The force between two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them: F = (1/4πε₀)(q₁q₂/r²), acting along the line joining them.

6. What is the value of the Coulomb constant 1/4πε₀ and the permittivity of free space ε₀?

   1/4πε₀ ≈ 9 x 10^9 N·m²/C², and ε₀ = 8.85 x 10^-12 C²/N·m².

7. How does Coulomb's force in a medium compare to that in vacuum?

   In a medium of relative permittivity (dielectric constant) K, the force is reduced by a factor K: F_medium = F_vacuum / K.

8. Define electric field intensity (E) and give its SI unit.

   The electric field at a point is the force experienced per unit positive test charge placed at that point: E = F/q₀. Its SI unit is newton per coulomb (N/C) or volt per metre (V/m).

9. What is the electric field due to a point charge Q at distance r?

   E = (1/4πε₀)(Q/r²), directed radially outward for positive Q and radially inward for negative Q.

10. State the superposition principle for electric fields.

    The net electric field at a point due to a group of charges is the vector sum of the individual electric fields produced by each charge independently.

11. What are electric field lines and what do they represent?

    Electric field lines are imaginary curves drawn such that the tangent at any point gives the direction of the electric field there, and their density (closeness) represents the field's magnitude.

12. List three key properties of electric field lines.

    1) They start on positive charges and end on negative charges. 2) They never intersect each other. 3) They are continuous, do not form closed loops in electrostatics, and are perpendicular to a conductor's surface.

13. Why can two electric field lines never cross each other?

    If they crossed, there would be two tangents (two directions of the electric field) at the point of intersection, which is impossible since the field has a unique direction at each point.

14. Define electric flux and give its formula.

    Electric flux is a measure of the number of field lines passing through a surface: Φ = E·A = EA cosθ, where θ is the angle between the field and the area vector (normal to the surface). SI unit: N·m²/C or V·m.

15. State Gauss's law.

    The total electric flux through a closed surface equals 1/ε₀ times the net charge enclosed: Φ = ∮E·dA = q_enclosed/ε₀.

16. Using Gauss's law, what is the electric field due to an infinitely long straight charged wire of linear charge density λ?

    E = λ/(2πε₀r), directed radially and inversely proportional to the perpendicular distance r from the wire.

17. Using Gauss's law, what is the electric field due to an infinite plane sheet of surface charge density σ?

    E = σ/(2ε₀), directed perpendicular to the sheet and independent of the distance from it.

18. What is the electric field due to a thin uniformly charged spherical shell, inside and outside?

    Outside (r ≥ R): E = (1/4πε₀)(q/r²), as if all charge were at the centre. Inside (r < R): E = 0.

19. Define electrostatic potential at a point and give its SI unit.

    It is the work done per unit positive charge in bringing a charge from infinity to that point without acceleration: V = W/q. SI unit: volt (V) = joule/coulomb.

20. What is the electric potential due to a point charge Q at distance r?

    V = (1/4πε₀)(Q/r). It is positive for a positive charge and negative for a negative charge, and is a scalar quantity.

21. What is the relationship between electric field and potential?

    The electric field is the negative gradient of potential: E = -dV/dr. The field points in the direction of decreasing potential.

22. Define potential difference between two points.

    The potential difference between two points is the work done per unit positive charge in moving it from one point to the other: V_AB = W_AB/q.

23. What is an equipotential surface?

    A surface on which the electric potential is the same at every point, so no work is done in moving a charge along it.

24. Why is the electric field always perpendicular to an equipotential surface?

    If the field had a component along the surface, work would be done in moving a charge along it, contradicting the definition of an equipotential surface (constant potential). Hence E must be perpendicular.

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