Important Questions for Class 12th Board Physics Paper

Electric Charges and Fields:
1. Define electric field and electric field intensity.
- Electric field is defined as the region around a charged object where its influence can be felt. It is a vector quantity that exerts force on other charged particles present in its vicinity.
- Electric field intensity is the measure of the force experienced by a unit positive charge placed at a point in an electric field. It is also a vector quantity and is given by the formula E = F/q, where E is the electric field intensity, F is the force experienced by the charge, and q is the magnitude of the charge.

2. State Coulomb's law and explain its significance.
- Coulomb's law states that the force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. Mathematically, it can be expressed as F = k(q1q2/r^2), where F is the force, q1 and q2 are the charges, r is the distance between them, and k is the electrostatic constant.
- This law is significant as it helps us understand and calculate the force between charged objects. It forms the basis of electrostatics and helps in various applications such as determining the force between protons and electrons in an atom, analyzing the behavior of charged particles, and designing electrical devices.

3. Explain Gauss's law and its applications.
- Gauss's law relates the electric flux passing through a closed surface to the net charge enclosed by that surface. Mathematically, it can be written as Φ = Q/ε0, where Φ is the electric flux, Q is the net charge enclosed, and ε0 is the permittivity of free space.
- This law is applicable in various situations, such as determining the electric field due to a uniformly charged infinite plane sheet, finding the electric field inside a uniformly charged sphere, and calculating the electric field due to a charged line.
- Gauss's law simplifies the calculation of electric fields in situations with high symmetry, making it a powerful tool in analyzing and solving complex electrostatic problems.

4. Differentiate between conductors and insulators.
- Conductors are materials that allow the free flow of electric charges. They have a large number of free electrons that can move easily in response to an applied electric field. Examples include metals like copper and aluminum.
- Insulators, on the other hand, are materials that do not allow the flow of electric charges. They have tightly bound electrons that do not move easily. Examples include rubber, glass, and plastic.
- Conductors have low resistivity and high conductivity, while insulators have high resistivity and low conductivity.
- Conductors efficiently transfer electric energy, while insulators hinder the flow of electric current.

- Conductors are used in electrical wiring, transmission lines, and electronic circuits, while insulators are used to provide insulation and prevent electrical leakage.

5. Explain the concept of electric potential and potential difference.
- Electric potential at a point is the amount of electric potential energy per unit charge. It is a scalar quantity and is measured in volts (V). It is given by the formula V = W/q, where V is the electric potential, W is the electric potential energy, and q is the charge.
- Potential difference, also known as voltage, is the difference in electric potential between two points in an electric field. It is a measure