Question

How does total internal reflection work and what are some examples of where you would observe it?

How does dispersion work and what are some examples of where you would observe it?

How does the focal length behave in terms of wavelenght, aberration, concave and convex mirros, and in converging and diverging lenses?

What is a coherent wave and what are the sources of coherent light?

Answer 1

Internal reflections are due to propagation of light from higher dens media to lower dens media .

Shining of an air bubble into water, Optical fibers etc are examples of total internal reflection .

Dispersion occurs due to splitting of white light (or polychrometic light) into its components .

The appearance of RAINBOW in sky , The multicolor pattern on prism are examples of dispersion of light

Focal length decreases for high wavelengths .Given by Cauchy's equation. because wavelength depends upon refractive index of medium which is inversly related to wavelength of a light.

In aberration focal length does not has a fixed value , it has a range of values ,converging/diverging differents rays at different points on optical axis.

Concave mirrors and concave lens has negative value of focal length while rest two have positive values.

coherents waves are wave which have time independent phase difference between any two points .

These are generated by a single point source .Or after some some diffractions (like fresnel diffraction ) in lab by passing through a combination of lenses