Recent Post

What are the negative effects of using chemicals?

What are the negative effects of using chemicals? Chemicals are used for different experiments in chemistry. But they can be harmful to humans and the environment when they are not properly used. i) Chemicals are used to keep fish and meat fresh and ripen fruits which is harmful to health. ii) Preservatives are used to preserve different food products which are risky for health. iii) Excessive use of chemical fertilizer harms plants. iv) Different harmful substances enter our bodies through blood by using artificial cosmetics, colors, etc. You may like What is Electrocardiograph? What is biological currency? What is activation energy? What is rate of reaction? What is green chemistry?

Physical Optics

Physical Optics Notes for Class 11 - 12

Poynting vector

The amount of energy passing through unit area placed perpendicular to direction of a electromagnetic wave propagating is called poynting vector.

Wave front

At any moment, locus of particles on a wave which are in phase is called wave front.

Plane wave front

Locus of particles which are in phase or parallel rays coming from infinity is called plane wave front.


The small rectangular opening which has long length but a very small width is called slit.

Coherent source

Two light sources are said to be coherent if they emit waves having constant phase difference.

Interference fringe

When interference takes place on a plane or screen, some parallel bright and dark lines or pattern are found. This bright or dark patterns are called interference fringes.


The spreading of light rays passing through narrow opening or around corner is called diffraction of light.

Fresnel's class of diffraction

Light source at finite distance emits light rays and when they travel round the corner and creates a fringe pattern on screen placed at finite distance. This pattern is called fresnel's class of diffraction.

Fraunhofer class of diffraction

Light rays coming from infinity creates a pattern on screen at infinity. It is called Fraunhofer class of diffraction.

Diffraction grating

A plastic slide having large number of equidistant slits used for measuring wavelength of light is called diffraction grating.

Grating constant

If width of each slit of a grating is a and each opaque scratch has width of b, (a+b) is called grating constant.


The process by which vibration of light of wave can be confined in a definite plane is called polarization.


Popular Posts

Finance and Business Finance

The Importance of Information and Communication Technology

Lessons on Life

Main components of computer systems


When you open the gas cylinder used for cooking, which action takes place first diffusion or effusion?