Frequently Asked Electrostatics Questions for Students
FAQs on Mastering Electrostatics: Practice Paper with Solutions
1. What is electrostatics and why is it important in physics?
Electrostatics is the branch of physics that studies electric charges at rest and their resulting forces, fields, and effects. It is important because it explains phenomena such as how static electricity forms, how charges interact through Coulomb's Law, and forms the foundation for understanding electric fields, capacitors, and insulators in both natural and technological contexts.
2. State and explain Coulomb's Law in electrostatics.
Coulomb's Law quantifies the force between two point charges at rest. It states:
- The magnitude of the electrostatic force between two charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
- Mathematically, F = (1/4πε0) × (q1q2/r2), where F is force, q1 and q2 are charges, r is distance, and ε0 is the permittivity of free space.
- This law is fundamental to understanding electric interactions.
3. What are conductors and insulators in electrostatics?
Conductors are materials that allow electric charges to flow freely, whereas insulators do not.
- Examples of conductors: Copper, Aluminum
- Examples of insulators: Rubber, Glass
- This difference is crucial in designing circuits and managing electric fields.
4. Explain the principle of superposition in electrostatics.
The superposition principle states that the total force or electric field acting at a point due to a system of charges is the vector sum of the forces or fields from each individual charge. This means effects from multiple charges simply add up, which helps to simplify calculations in complex electrostatic problems.
5. What is an electric field, and how is it represented?
An electric field is a region around a charged object where another charge experiences a force. It is represented by electric field lines which:
- Originate on positive charges and end on negative charges
- Are denser where the field is stronger
- The direction of the field is the direction a positive test charge would move
- The magnitude is given by E = F/q where F is force and q is the test charge.
6. Define the concept of electric potential in electrostatics.
Electric potential at a point is the work done to bring a unit positive charge from infinity to that point.
- Measured in volts (V)
- Scalar quantity
- Helps determine the energy changes and charge flow in a circuit and fields.
- Formula: V = W/q, where W is work done and q is charge.
7. What are the applications of electrostatics in daily life and technology?
Electrostatics has various practical applications, including:
- Photocopiers and laser printers (use static electricity to attract toner)
- Electrostatic precipitators (remove dust from industrial gases)
- Paint spraying (even coating using static charges)
- Everyday static shocks and lightning
8. What is Gauss's Law, and how is it used in electrostatics?
Gauss's Law states that the total electric flux through a closed surface equals 1/ε0 times the total enclosed charge. It is written as Φ = ∮E·dA = Qenclosed/ε0.
- Useful for calculating electric fields in simple, symmetrical cases (spheres, cylinders, planes).
- Makes solving electrostatics problems easier when symmetry is present.
9. What factors affect the force between two charges?
The force between charges depends on:
- The magnitude of each charge (directly proportional)
- Distance between them (inversely proportional to the square of the distance, r2)
- The nature of the medium (affected by permittivity)
This relationship is described by Coulomb's Law.
10. Can you explain the differences between electric field and electric potential?
Electric field and electric potential are related but different concepts:
- Electric field is a vector; it shows the direction and strength of the force acting on a charge at a point.
- Electric potential is a scalar; it measures the work done per unit charge to bring a charge from infinity.
- High electric field doesn't always mean high electric potential and vice versa.
Both are essential for understanding electrostatics for CBSE and other school-level exams.
11. What is meant by quantization of charge?
Quantization of charge means that electric charge exists in discrete packets, not as a continuous value.
- The smallest unit is the charge of an electron (e = 1.6 × 10-19 C).
- All observable charges are integer multiples of e.
This is a fundamental property listed in the CBSE and NCERT syllabus.
12. What are the properties of electric lines of force?
Electric lines of force, or field lines, have these properties:
- They never cross each other.
- Originate on positive charges, terminate on negative charges.
- The tangent at any point gives the direction of the field.
- Density indicates field strength.
These help in visualizing and understanding electric fields.






















