Class 12 Electrostatics



Watch the lecture on Electrostatics 




Answer the questions given below

Electric Charges and Fields                                                                                                         Chapter 1

Fill in the blanks

1.     The property which differentiates the two kinds of charges is called the _____________ of charge.
2.      A simple apparatus to detect charge on a body is called _______________ electroscope.
3.      To electrify a neutral body, we need ____________ or ___________ one kind of charge.
4.      Some substances readily allow passage of electricity through them are called ______________
5.      When we bring a charged body in contact with the earth, all the excess charge on the body disappears by causing a momentary current to pass to the ground through the connecting conductor (such as our body). This process of sharing the charges with the earth is called ________________.
6.      Metallic bodies of the electric appliances such as electric iron, refrigerator, TV are connected to the
     ________ wire. When any fault occurs or live wire touches the metallic body, the charge flows to
      the _______ without damaging the appliance and without causing any injury to the humans
7.      The total charge of a system containing five charges +1, +2, –3, +4 and –5, in some arbitrary unit,
Is __________.
8.      The total charge of an isolated system is always ______________.
9.      The fact that electric charge is always an integral multiple of e is termed as ­­­­­­­­­­­­­­­_______________ of charge.
10. The quantization of charge was first suggested by the experimental laws of electrolysis discovered by English experimentalist _______________.
11. It was experimentally demonstrated by __________ in 1912.
12. The value of the basic unit of charge is____________________.
13. The force between two point charges and found that it varied inversely as the square of the distance between the charges and was directly proportional to the product of the magnitude of the two charges and acted along the line joining the two charges. This law is known as _________________.
14. The value of k = 1/4ε0 in SI units is _________________.
15. The value of ε0 in SI units is  εo = ___________________ C2 N–1m–2
16. Electric field due to positive charge is _______________ and that due to negative charge is _____________.
17. The direction of an area element is along its ____________________.
18. The unit of electric flux is ______________.
19. An electric dipole is a pair of _____ and ________ point charges, separated by a distance 2a.
20. The direction from _____ to ______ is said to be the direction of the dipole.
21. The ­­­ _________ of –q and q is called the centre of the dipole.
22. The total charge of the electric dipole is ______________.
23. The dipole field at large distances falls off not as 1/r 2 but as __________.
24. The magnitude and the direction of the dipole field depends not only on the distance r but also on the _____ between  _________ and ___________.
25. Molecules with permanent electric dipole moment are called ______________.
26. At __________________ angle a dipole has max torque in uniform electric field and minimum at _________________ angle.
27. Electric flux through a closed surface S is __________.
28. The total electric flux through a closed surface is zero if no __________ is enclosed by the surface.
29. Gauss’s law is true for any closed surface, no matter what its ___________ or _____________.
30. Electric field inside a charged 

One word answer questions

1. What charge appears on glass rod when rubbed with silk cloth?
2. What charge appears on plastic rod when rubbed with cat fur?
3. Which scientist gave names to the two charges as positive and negative?
4. When a charged rod is brought near a charged gold leaf electroscope, if the leaves moves apart what does it indicate?
5. When a charged conductor touches another uncharged conductor, what happens?
6. What are the basic properties of charges?
7. What is the force between two charges separated by a distance ‘r’ in vacuum?
8. In the above question, what happens to force if a material medium is introduced between the two charges?
9. What is relative permittivity?
10. Write the force between two charges in vector notation.
11. A charge exerts a force 12 N on another charge. What is the force exerted by the second charge on the first?
12. Which principle is used to calculate force on a charge due to n numbers of charges?
13. What is the relation between electric field and distance?
14. What is the SI unit of electric field?
15. Write two properties of electric field.
16. What is the SI unit of electric flux?
17. What is the electric field on axial line of a dipole?
18. What is the electric field on equatorial plane of a dipole?
19. Give two examples of non polar molecules.
20. Write the equation for torque acting on a dipole in uniform magnetic field.
21. Draw a diagram showing the stable and unstable equilibrium of dipole in uniform magnetic field.
22. What is linear charge density, surface charge density and volume charge density?
23.  How much flux comes out of a spherical surface enclosing a charge 2q?
24. In the above question if the radius of the sphere is increased/ decreased, what flux comes out?

25. What is the electric field due to charged infinite plane sheet?


Note: 
            Submit the answered work sheet by March 30, 2020, to respective email address given below.

Class:  12 A1  to   physics1dps@gmail.com

Class:  12 A2  to   physics2dps@gmail.com











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