Wave optics

-

                                                                                                                          By~Tarachand Tak 

In 1637 Descartes gave the corpuscular model of light and derived Snell’s law. It explained the laws of reflection and refraction of light at an interface. 

The corpuscular model predicted that if the ray of light (on refraction) bends towards the normal then the speed of light would be greater in the second medium. This corpuscular model of light was further developed by Isaac Newton in his famous book entitled OPTICKS.

In 1678, the Dutch physicist Christiaan Huygens put forward the wave theory of light – it is this wave model of light, wave model could satisfactorily explain the phenomena of reflection and refraction

Different colour of light has different wavelength. for example, the wavelength of yellow light is about 0.6 um

 light waves also propagate through vacuum had no require of medium. This was explained when Maxwell put forward his famous electromagnetic theory of light. he propounded that light must be an electromagnetic wave.

Thus, according to Maxwell, light waves are associated with changing electric and magnetic fields. changing electric field produces a time and space varying magnetic field and a changing magnetic field produces a time and space varying electric field.

HUYGENS PRINCIPLE

Wavefront : the locus of all points, where the particles of the medium vibrate with the same phase.

The speed with which the wavefront moves outwards from the source is called the speed of the wave.

The energy of the wave travels in a direction perpendicular to the wavefront

     Types of Wavefront:-


Each point of the wavefront is the source of a secondary disturbance and the wavelets emanating from these points spread out in all directions with the speed of the wave. 

These wavelets emanating from the wavefront are usually referred to as secondary wavelets and if we draw a common tangent to all these spheres, we obtain the new position of the wavefront at a later time.


REFRACTION AND REFLECTION OF PLANE WAVES USING HUYGENS PRINCIPLE

✌Refraction of a plane wave


This is the Snell’s law of refraction.

✌Reflection of a plane wave by a plane surface


The triangles AEC and A'BC are congruent, meaning

.

- Difference wavefront for different Shapes 

COHERENT AND INCOHERENT ADDITION OF WAVES

Interference is based on the superposition principle according to which at a particular point in the medium,
The phase difference between the displacements produced by each of the waves does not change with time; when this happens the two sources are said to be coherent.


The intensity is proportional to the square of the amplitude 

                                                      ---------------------WAIT---------------------

Comments

Post a Comment

Popular posts from this blog

Journey to the end of the Earth (By- Tishani Doshi)

-
Image
                                                                                                                      Made BY~❤Tarachand Tak ❤ EARLY this year, I found myself aboard a Russian research vessel — the Akademik Shokalskiy — heading towards the coldest, driest, windiest continent in the world: Antarctica. My journey began 13.09 degrees north of the Equator in Madras , and involved crossing nine time zones, six checkpoints, three bodies of water, and at least as many ecospheres.     By the time I actually set foot on the Antarctic continent I had been travelling over 100 hours in combination of a car, an aeroplane and a ship ; so, my first emotion on facing Antarctic...
Read more

Chemical kinetics Formula for jee and neet

-
Image
Chemical kinetics  is the study of the rate at which chemical reactions occur. It helps us understand the factors affecting these rates, the mechanism of the reaction, and the sequence of events that lead to the formation of products. Rate of a Chemical Reaction Rate of Reaction is the change in concentration of reactants or products per unit time. Where: [A] is the concentration of reactant A. a is the stoichiometric coefficient of A in the balanced chemical equation. Graphically, the rate is represented by the negative of slope of the concentration vs. time graph for reactants, and the positive slope for products. Factors Affecting Rate of Reaction Concentration of Reactants:  Rate usually increases with increasing concentration. Temperature:  Typically, rate increases with temperature. Presence of Catalyst:  Catalysts can increase the rate. Surface Area:  Especially in solid reactions, greater surface area can lead to faster rates. Pressure:  Especially ...
Read more