ELECTROMAGNETIC WAVES In this unit, the student is exposed to • the displacement current • Maxwell’s correction to Ampere's circuital law • Maxwell’s equation in integral form • production and properties of electromagnetic waves – Hertz’s experiment • sources of electromagnetic waves • electromagnetic spectrum “One scientific epoch ended and another began with James Clerk Maxwell” – Albert Einstein Learning Objectives Figure . Visible spectrum – rainbow and lightning We see the world around us through light. Light from the Sun is one of the sources of energy without which human beings cannot survive in this planet. Light plays crucial role in understanding the structure .
INTRODUCTION and properties of various things from atom to universe. Without light, even our eyes cannot see objects. What is light?. This puzzle made many physicists sleepless until middle of th century.
Earlier, many scientists thought that optics and electromagnetism are two different branches of physics. But from the work of James Clerk Maxwell, who actually enlightened the concept of light from his theoretical prediction that light is an electromagnetic wave which moves with the speed equal to × ms – (in free space or vacuum). Later, it was confirmed that visible light is just only small portion of electromagnetic spectrum, which ranges from gamma rays to radio waves. In unit , we studied that time varying magnetic field produces an electric field (Faraday’s law of electromagnetic induction).
Maxwell strongly believed that nature must possess symmetry and he asked 12th - 12th - - - - - Unit Electromagnetic waves In today's digital world, cell phones (Figure . (a)) have greater influence in our day to day life. It is a faster and more effective mode of transferring information from one place to another. It works on the basis that light is an electromagnetic wave.
In hospitals, the location of bone fracture can be detected using X-rays as shown in Figure . (b), which is also an electromagnetic wave. For cooking microwave oven is used. The microwave is also an electromagnetic wave.
There are plenty of applications of electromagnetic waves in engineering, medicine (example LASER surgery, etc), defence (example, RADAR signals) and also in fundamental scientific research. In this unit, basics of electromagnetic waves are discussed. . .
Displacement current and Maxwell’s correction to Ampere's circuital law Induced magnetic field Faraday’s law of electromagnetic induction states that the change in magnetic field produces an electric field. Mathematically, it is written as E dl d dt d dt B dA l