Unit 01 - ElectroStatics Class XII CBSE Question Bank

ElectroStatics

(At present all the questions are posted together; soon we will be categorizing according to marks)

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1. What is Frictional electricity? (1)


2. When can we say that a body is charged?(1)


3. What is electric charge? Is it a scalar or a vector quantity? (1)


4. What is electrostatics? (1)


5. Describe an experiment to show that there are two kinds of charges. (2)


6. Describe an experiment to show that like charges repel and unlike charges attract. (2)


7. Describe the electronic theory of frictional electricity. (2)


8. Write the differences between conductors and insulators. (2)


9. What is meant by electrostatic induction?


10. Distinguish charging by induction and charging by conduction. (2)


11. How can you charge a piece of metal positively without touching it? (2)


12. Explain the additive nature of electric charge. (2)


13. What do you mean by quantization of electric charge? (1)


14. Calculate the number of electrons missing in a body with 1 coulomb positive charge. (1)


15. If a body loses 10⁹ electrons every secon, calculate the time required by it to acquire 1 C positive charge.


16. Estimate the charge constituted by the total number of electrons present in a cup of water.


17. Determine the total charge of 1 kg of electrons.


18. State the law of conservation of charge. (1)


19. Write the difference between mass and charge. (2)


20. State Coulomb's law in electrostatics. (1)


21. Define one coulomb. (1)


22. Express Coulomb's law in vector form. (1)


23. Express coulomb's law in terms of position vectors.


24. State the principle of superposition of electrostatic forces.


25. Show that coulomb's force obeys Newton's III law.


26. Define permitivity of a medium.


27. Define relative permitivity of a medium


28. Define relative permitivity of a medium on the basis of Coulomb's law.


29. The electrostatic force of repulsion between two positively charged bodies is 3.7 x 10^-9 N, when they are separated by a distance of 5 A^o How many electrons are missing in each?

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LONG ANSWER QUESTIONS

1. Obtain an expression for the electric field intensity due to a uniformly charged ring of radius r at a point on the axis of the ring.


2. Express Coulomb's law in vector for.


3. Derive an expression for the electric field due to an electric dipole at a point on (a) the axial line (b) the equatorial line.


4. Derive an expression for the torque acting on an electric dipole placed in a uniform electric field.


5. Show that the work done in rotating an electric dipole of dipole moment p in a uniform electric field E by an angle θ from the equilibrium postition W = PE(1-cos θ)


6. Derive Coulomb's law from Gauss' law.


7. Use Gauss theorem to derive an expression for the electric field at a point due to an infinite plane sheet of charge of uniform charge density σ


8. Use Gauss theorem to derive an expression for the electric field at a point due to a thin infinitely long straight line  of charge of uniform charge density λ


9. Derive an expression for the electric field at a point due to uniformly charged spherical shell using Gauss' law.


10. Derive an expression for the capacitance of a parallel plate capacitor.


11. Find the equivalent capacitance of three capacitors of capacitances C1, C2 and C3 connected in (1) series (2) parallel


12. Derive an expression for the electric potential due to a point charge q at a distance r from it.


13. Giving a labeled diagram explain the principle and working of a Van de Graaff generator.


14. A dielectric slab of thickness t introduced between the plates of a parallel plate capacitor separated by a distance d. (t < d). DEerive an expression for the capacitance of the capacitor.