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Semiconductor and Electronics

Semiconductor and Electronics Notes for Class 11 - 12 Learning Outcomes Explain band theory of solid materials Explain conductor, non-conductor, and semiconductor by band theory Explain intrinsic and extrinsic semiconductors Explain the concept of electron and hole in semiconductors Explain the p-type and n-type semiconductor Explain the construction and function of the junction diode Explain rectification Explain the construction and function of a junction transistor Explain the use of transistor as amplifier and switch Explain conversion of a different number system Explain Binary operation Analysis of the program of different logic gate Explain band theory of solid materials Energy Band:   There is a slight difference in the energy of electrons revolving in the same orbit in an atom of any matter. The range between the maximum and minimum energy level of these electrons situated in the same orbit is called the energy band. The energy level and energy band are not the same. The energ


Astronomy Notes for Class 11-12

Big Bang

The expansion of universe indicates an initial point from where it is expanding. About 15 hundred crore years ago it started from space time singularity. 

At the beginning, it was infinitely dense and infinitely hot and it expands after big bang in all directions. After starting to expand it become cooler and goes through some intermediate changes.

If a star has enough mass and density then its gravity field will be so strong that no light can emit from that star. Before travelling away from the star, gravitational field will be so strong that no light can emit from that star. 

Before traveling away from the star, gravitational pull will take that back. Scientist Michell thought that this type of stars can be in huge amount. We can not see those stars because no light emits from them. We can only feel the gravitational pull those of that object. These objects are called black hole.

Artificial Satellite

A man made spacecraft at a definite height from ground can orbit earth like moon. This spacecraft is called artificial satellite.


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