1. What is the principle of conservation of charge?
Answer: The principle of conservation of charge states that the total electric charge in an isolated system remains constant over time; it cannot be created or destroyed, only transferred from one object to another.
2. Explain Coulomb’s law and its significance.
Answer: Coulomb’s law describes the electrostatic force between two charged particles. It states that the force is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. Coulomb’s law is fundamental in understanding interactions between charged objects.
3. How does the superposition principle apply to forces between multiple charges?
Answer: The superposition principle states that the net force exerted on a charged particle by multiple other charges is the vector sum of the forces exerted by each individual charge acting independently.
4. Describe the concept of electric field due to a point charge.
Answer: The electric field due to a point charge is the force per unit positive charge experienced by a test charge placed at a certain point in space around the charge. It points radially outward from a positive charge and radially inward towards a negative charge.
5. What are electric field lines?
Answer: Electric field lines are imaginary lines that represent the direction and magnitude of the electric field around a charged object. They start from positive charges and end at negative charges, with the density of lines indicating the strength of the field.
6. Explain the concept of an electric dipole.
Answer: An electric dipole consists of two equal and opposite point charges separated by a small distance. It has a characteristic dipole moment vector pointing from the negative to the positive charge.
7. How is the electric field calculated due to a dipole?
Answer: The electric field due to a dipole can be calculated using the formula
where kkk is the Coulomb constant, ppp is the magnitude of the dipole moment, and rrr is the distance from the dipole.
8. What is the torque experienced by a dipole in a uniform electric field?
Answer: The torque τ experienced by a dipole in a uniform electric field E is given by the formula
where p is the magnitude of the dipole moment and θ is the angle between the dipole moment vector and the electric field vector.
9. Define electric flux and Gauss’s law.
Answer: Electric flux is a measure of the total number of electric field lines passing through a given area. Gauss’s law states that the electric flux through a closed surface is proportional to the total charge enclosed by that surface, divided by the electric constant ε0
10. How is Gauss’s law applied to find the electric field due to an infinitely long uniformly charged straight wire?
Answer: By applying Gauss’s law, one can find that the electric field E due to an infinitely long uniformly charged straight wire at a distance r from the wire is given by
where λ is the linear charge density.
11. Discuss the application of Gauss’s law to find the electric field due to a uniformly charged infinite plane sheet.
Answer: Gauss’s law can be used to show that the electric field E due to a uniformly charged infinite plane sheet is independent of distance from the sheet and is given by
where σ is the surface charge density.
12. Explain how Gauss’s law is applied to find the electric field due to a uniformly charged thin spherical shell.
Answer: Gauss’s law can be used to show that the electric field E inside and outside a uniformly charged thin spherical shell is zero and equivalent to that of a point charge located at the center of the shell, respectively.
13. Define electric potential and how it is calculated for a point charge.
Answer: Electric potential, also known as voltage, is the amount of work required to move a unit positive charge from infinity to a point in an electric field. The electric potential V due to a point charge Q at a distance r is given by
where k is the Coulomb constant.
14. Explain the concept of potential difference.
Answer: Potential difference, also known as voltage difference, is the difference in electric potential between two points in an electric field. It represents the work done per unit charge in moving a charge between the two points and is measured in volts (V).
15. What are equipotential surfaces?
Answer: Equipotential surfaces are surfaces in an electric field where the electric potential is constant at every point. Electric field lines are always perpendicular to equipotential surfaces.
16. Discuss electrical potential energy and its calculation for a system of two point charges.
Answer: Electrical potential energy is the energy stored in a system of charges due to their positions in an electric field. The electrical potential energy U of a system of two point charges q1 and q2 separated by a distance r is given by
17. Differentiate between conductors and insulators.
Answer: Conductors are materials that allow electric charges to flow freely through them, while insulators are materials that do not allow electric charges to flow easily.
18. Explain dielectrics and electric polarization.
Answer: Dielectrics are insulating materials that can become polarized when placed in an electric field, with positive and negative charges separated within the material. This polarization reduces the overall electric field within the dielectric.
19. Define capacitance and discuss the combination of capacitors in series and parallel.
Answer: Capacitance is the ability of a system to store electric charge. Capacitors in series have an equivalent capacitance given by
while capacitors in parallel have an equivalent capacitance given by
20. How is the energy stored in a capacitor calculated?
Answer: The energy stored in a capacitor U is given by
where C is the capacitance of the capacitor and V is the voltage across it.