Electrostatics: Electric Charges and Fields - Important Questions for Higher Secondary
Electrostatics: Electric Charges and Fields - Important Questions for Class 12
Key Questions and Answers on Electrostatics: Electric Charges and Fields
1. What is Coulomb's Law?
Answer: Coulomb's Law states that the force of attraction or repulsion between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. Mathematically,
where is the force between the charges, and are the charges, is the distance between the charges, and is Coulomb's constant.
2. What is an electric field and how is it represented?
Answer: An electric field is a region around a charged particle where a force would be experienced by other charges. The electric field due to a point charge at a distance is given by:
The electric field is represented by field lines, which originate from positive charges and terminate at negative charges.
3. Explain Gauss's Law in electrostatics.
Answer: Gauss's Law states that the net electric flux through a closed surface is proportional to the enclosed electric charge. Mathematically,
where is the electric flux, is the electric field, is the differential area, is the enclosed charge, and is the permittivity of free space.
4. What is the principle of superposition of electric fields?
Answer: The principle of superposition states that the net electric field due to multiple charges is the vector sum of the electric fields due to each individual charge. If are the electric fields due to charges , then the net electric field is given by:
5. Define electric dipole moment and derive the expression for the electric field due to a dipole on its axial line.
Answer: An electric dipole consists of two equal and opposite charges separated by a distance . The electric dipole moment is defined as:
The electric field due to a dipole on its axial line at a point distant from the center of the dipole is given by:
6. What is the significance of the permittivity of free space ()?
Answer: The permittivity of free space is a fundamental constant that characterizes the ability of the vacuum to permit electric field lines. It appears in Coulomb's Law and Gauss's Law and affects the force between charges in a vacuum. Its value is approximately .
7. How is the electric field due to a uniformly charged spherical shell calculated?
Answer: For a uniformly charged spherical shell:
Outside the shell, the electric field is as if all the charge were concentrated at the center.
Inside the shell, the electric field is zero. The electric field outside at a distance is given by:
where is the total charge on the shell.
8. What are the applications of electrostatics in daily life?
Answer: Electrostatics has various applications including:
Photocopiers and laser printers.
Electrostatic precipitators for pollution control.
Capacitors in electronic circuits.
Painting and powder coating processes.
9. Derive the expression for the potential energy of a system of two point charges.
Answer: The potential energy of a system of two point charges and separated by a distance is given by:
This represents the work done in bringing the charges from infinity to a distance apart.
10. Explain the concept of electric potential and potential difference.
Answer: Electric potential at a point is the work done per unit charge in bringing a positive test charge from infinity to that point. Potential difference between two points is the work done in moving a unit charge from one point to the other. It is measured in volts (V).
Conclusion
Understanding the fundamental concepts of electrostatics is crucial for students in Class 12. These questions cover essential aspects of electric charges and fields, providing a solid foundation for further studies. Stay tuned for more insightful content on MightyKnowledge!
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