ELECTROSTATICS

What is meant by charge on a capacitor?

Mohit asked this question:

“What is meant by charge on a capacitor?”

Answer: As we know, a simple capacitor (say a parallel plate capacitor) consists of two plates parallel to each other. When charged, charge on either plate of the capacitor is called charge on the capacitor.

The following links will help you explore further and understand more

• http://www.kpsec.freeuk.com/components/capac.htm
• http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capac.html
• http://www.youtube.com/watch?v=zNpbdptwxlQ
• http://www.youtube.com/watch?v=qdXbnhb1bVo&feature=related

Electrostatics : A Practice Test Paper – 1

Time: 45 min

Max. Marks: 25

1. How does the force between two point charges change, if the dielectric constant of the medium in which they are kept, increases? [1]
2. Name the experiment which established the quantum nature of electric charge. [1]
3. Ordinary rubber is an insulator, but the special tyres of aircrafts are made slightly conducting. Why is this necessary? [1]
4. Draw electric field lines around an electric dipole. [1]
5. What would be the work done if a point charge +q is taken from  a point A to B on the circumference of a circle with another point charge +q at the centre? [1]
6. Obtain an expression for the potential energy of two charges q1 and q2 separated by distance r in a electric field E. [2]
7. Define electric field intensity. What is its SI unit? What is the relation between electric field and force on the charge? [2]
8. Obtain an expression for the electric potential at a point due to an electric dipole. [3]
9. Sketch equipotential surfaces for (i) a positive point charge (ii) Two equal positive point charges separated by a small distance (iii) a uniform electric field. [3]
10. (a) State Gauss Law (b) Using it derive an expression for the electric field intensity at a point near a thin infinite plain sheet of charge. (c) A point charge of 2 microcoulomb is at the centre of a cubic Gaussian surface 9cm edge. What is the net electric flux through all the surfaces of the cube? [5]
11. (a) Define electric dipole moment. (b) Derive expression for electric field intensity of a dipole at a point on its axial line. (c) Two charges +10μ C and – 10 μ C are placed 5 mm apart. Determine the electric field at a point P 15 cm away from its centre O on a line passing through O and normal axis of the dipole. [5]

Electrostatics Question Banks

Objective Type Questions from Electrostatics

Electrostatics Question Bank from TutorNext

Electrostatics Question Bank from 2lv.in

ELECTROSTATICS TEST PAPER FOR CLASS XII

1. What orientation of an electric dipole in a uniform electric field corresponds to its stable equilibrium?

2. What is the area of the plates of a parallel plate capacitor of capacitance 2F and with separation between plates 0.5 cm?

3. What is the work done in carrying a point charge 10 nC between two points separated by a distance 5 cm on an equipotential surface?

4. A parallel plate capacitor is made by stacking ‘n’ equally spaced plates connected alternatively. If the capacitance between any two plates is ‘C’, determine the resultant capacitance of the combination

5. Calculate the coulomb force between two a particles separated by a distance of 3.2 x 10^-15 m

6. Draw graph showing variation of electric field with distance for a uniformly charged metallic sphere.

7. An electron and proton are free to move in an electric field. Which one will have greater acceleration? Why?

8. Sketch two equipotential surfaces for (a) a point charge. (b) between two plane sheets of charge.

9. 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)

10. The given graph shows the variation of charge ‘q’ verses potential difference for two capacitors C1 and C2 .The capacitors have same plate separation, but the plate area of C2 is double that of C1.Identify the line in the graph corresponding to C1 & C2 and why?

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

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

13. You are given three capacitors of value 2μF, 3μF, 6μF. How will you connect them to a resultant capacity of 4μF?

14. Two equally charged identical metal spheres A and B repel each other with a force of 2·0 x 10^-5 N. Another identical uncharged sphere C is touched to A and then placed at the mid point between A and B. What is the net force on C?

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

16. Describe the principle construction and working of a Van de graff Generator with the help of a neat labeled diagram.

17. Use Gauss theorem to derive an expression for the electric field at a point due to

a. an infinite plane sheet of charge of uniform charge density σ

b. a thin infinitely long straight line  of charge of uniform charge density λ

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Electric Potential – Notes

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Electrostatics Notes – Module II (Electric field, Dipole, Gauss Theorem)

Click the Link below to download Electrostatics Notes – Module II (Electric field, Dipole, Gauss Theorem and Applications)

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