Important Questions of CBSE Class 12 Physics Chapter 1: Electric Charges and Fields

1. What is an electric charge?
An electric charge is a fundamental property of matter that gives rise to electric forces. It can be positive or negative, and like charges repel while opposite charges attract each other.

2. What is the SI unit of electric charge?
The SI unit of electric charge is the Coulomb (C).

3. What is conservation of electric charge?
The principle of conservation of electric charge states that the total electric charge in an isolated system remains constant. Electric charge can neither be created nor destroyed, only transferred from one object to another.

4. Define an electric field.
An electric field is a region in which an electric charge experiences a force. It is a vector quantity, and its direction is the direction in which a positive test charge would experience a force.

5. What is the formula for electric field intensity due to a point charge?
The formula for electric field intensity (E) due to a point charge (Q) at a distance (r) is given by E = kQ/r^2, where k is the electrostatic constant (9 × 10^9 Nm^2/C^2).

6. State Gauss's law.
Gauss's law states that the total electric flux through any closed surface is equal to the ratio of the total charge enclosed by the surface to the permittivity of free space (ε0).

7. What is an electric dipole?
An electric dipole consists of two equal and opposite charges separated by a small distance. The dipole moment (p) is the product of the charge (q) and the separation distance (d) between the charges, i.e., p = qd.

8. Explain the principle of a Van de Graaff generator.
A Van de Graaff generator is based on the principle of electrostatic induction. It consists of a large metal sphere mounted on an insulating column. A rubber belt is used to transfer charge from a high-voltage source to the metal sphere. The charge accumulates on the sphere, creating a high electric potential.

9. What is the difference between conductors and insulators?
Conductors are materials that allow the flow of electric charges through them easily. They have free electrons that can move within the material. Insulators, on the other hand, do not allow the flow of electric charges easily. They have tightly bound electrons that do not move freely.

10. Explain Coulomb's law.
Coulomb's law states that 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. The force is along the line joining the charges and follows the inverse square law.

These are some important questions from CBSE Class 12 Physics Chapter 1: Electric Charges and Fields. Understanding these concepts and their applications will provide a strong foundation in the subject.