Electricity and Magnetism

After completion of this unit, student must be able to:

  • Interpret the unit of electricity and use them in measurement.
  • Demonstrate the Ohm's law and show the inter-relation between ampere, volt and ohm.
  • Point out the factors affecting resistance.
  • Demonstrate and define the magnetic field and magnetic lines of force.
  • Explain the components of terrestrial magnetism.


Potential Difference, Electromotive Force and Ohm's Law

The e.m.f. of an electric source is the rate at which energy in a non-electrical form is converted into an electrical form during the passage of unit positive charge through it. This note provides an information on potential difference, electromotive force and Ohm's law.


An instrument or a device that changes a non-electrical energy into electrical energy is called the sources of electricity. The electricity that is possessed due to change in the number of electrons in bodies is called current electricity. This note provides an information about electric charge, sources of electricity, electric circuit, conductor and insulators, conventional current flow, ammeter and galvanometer.

Magnetic Field and Magnetic Lines of Force

The space around a magnet, where magnetic force can be felt by a magnetic body is called magnetic field of that magnet. This note provide us the information of magnetism, neutral point and properties of magnet.

Earth’s Magnetic Field

A freely suspended bar magnet always comes to rest in a north-south direction. Neutral points are obtained on the magnetic field of a magnet which is due to the combined effects of its magnetic field and earth’s magnetism. This note provides us the information about terrestrial magnetism, magnetic meridian and geographical meridian and magnetic elements of earth's magnetic fields.


The resistance of a conductor can be defined as the property of the conductor that opposes the flow of electric current through it. This note provides information about resistance, factor affecting resistance, resistivity and conductivity.