Physics 12 Electrostatics Notes
ELECTROSTATICS - I – Electrostatic Force
1. Frictional Electricity 2. Properties of Electric Charges 3. Coulomb’s Law 4. Coulomb’s Law in Vector Form 5. Units of Charge 6. Relative Permittivity or Dielectric Constant 7. Continuous Charge Distribution i) Linear Charge Density ii) Surface Charge Density iii) Volume Charge Density
Frictional Electricity:
Frictional electricity is the electricity produced by rubbing two suitable bodies and transfer of electrons from one body to other.
+ ++
++
+ ++
+
+ ++
Glass Silk
+ ++ + + ++ + ++
- - - -
.- - Ebonite Flannel
Electrons in glass are loosely bound in it than the electrons in silk. So, when glass and silk are rubbed together, the comparatively loosely bound electrons from glass get transferred to silk. As a result, glass becomes positively charged and silk becomes negatively charged. Electrons in fur are loosely bound in it than the electrons in ebonite. So, when ebonite and fur are rubbed together, the comparatively loosely bound electrons from fur get transferred to ebonite. As a result, ebonite becomes negatively charged and fur becomes positively charged.
It is very important to note that the electrification of the body (whether positive or negative) is due to transfer of electrons from one body to another. i.e. If the electrons are transferred from a body, then the deficiency of electrons makes the body positive. If the electrons are gained by a body, then the excess of electrons makes the body negative. If the two bodies from the following list are rubbed, then the body appearing early in the list is positively charges whereas the latter is negatively charged. Fur, Glass, Silk, Human body, Cotton, Wood, Sealing wax, Amber, Resin, Sulphur, Rubber, Ebonite. Column I (+ve Charge) Glass Wool, Flannel Ebonite Dry hair Column II (-ve Charge) Silk Amber, Ebonite, Rubber, Plastic Polythene Comb
Properties of Charges:
1. There exists only two types of charges, namely positive and
1. Frictional Electricity 2. Properties of Electric Charges 3. Coulomb’s Law 4. Coulomb’s Law in Vector Form 5. Units of Charge 6. Relative Permittivity or Dielectric Constant 7. Continuous Charge Distribution i) Linear Charge Density ii) Surface Charge Density iii) Volume Charge Density
Frictional Electricity:
Frictional electricity is the electricity produced by rubbing two suitable bodies and transfer of electrons from one body to other.
+ ++
++
+ ++
+
+ ++
Glass Silk
+ ++ + + ++ + ++
- - - -
.- - Ebonite Flannel
Electrons in glass are loosely bound in it than the electrons in silk. So, when glass and silk are rubbed together, the comparatively loosely bound electrons from glass get transferred to silk. As a result, glass becomes positively charged and silk becomes negatively charged. Electrons in fur are loosely bound in it than the electrons in ebonite. So, when ebonite and fur are rubbed together, the comparatively loosely bound electrons from fur get transferred to ebonite. As a result, ebonite becomes negatively charged and fur becomes positively charged.
It is very important to note that the electrification of the body (whether positive or negative) is due to transfer of electrons from one body to another. i.e. If the electrons are transferred from a body, then the deficiency of electrons makes the body positive. If the electrons are gained by a body, then the excess of electrons makes the body negative. If the two bodies from the following list are rubbed, then the body appearing early in the list is positively charges whereas the latter is negatively charged. Fur, Glass, Silk, Human body, Cotton, Wood, Sealing wax, Amber, Resin, Sulphur, Rubber, Ebonite. Column I (+ve Charge) Glass Wool, Flannel Ebonite Dry hair Column II (-ve Charge) Silk Amber, Ebonite, Rubber, Plastic Polythene Comb
Properties of Charges:
1. There exists only two types of charges, namely positive and