Recent Posts - page 3

  • Semiconductors and charge carriers

    Semiconductors and charge carriers: the copper atom's electronic configuration. There are 29 electrons and 9 protons in the copper atom which makes it electrically neutral. Together with 28 electrons in the first 3 shells ( K, L, M ) and the 28 protons in the nucleus the copper atom's core has a net charge of + 1 e. The electron in the outermost N shell has only 1 electron known as the valence electron. Photo-Credit:

    Analog electronics and applications

    Conductors, semiconductors and holes as charge carriers

    Topics covered in this lecture

    A. Conductors

    B. Semiconductors

    C. Holes

    D. Intrinsic semiconductors

    Conductors: A conductor is the name of a material which is a good conductor of electricity. Copper ( Cu ), Silver ( Ag ) and Gold ( Au ) are examples of materials which are good conductors of electricity, in other words they are known as conductors. 

    A natural question arises as to why copper is a good conductor of electricity. Such a fact can be understood from its electronic configuration.

    Electronic configurations are a good way to understand the physical as well as chemical properties of materials. A great deal of our modern understanding of materials and their properties are based on the detailed electronic configuration facts of the same.  

    The copper has 29 electrons in its atom. That means it has an equal number of protons. It has two isotopes, one has 34 and the other has 36 neutrons. Isotopes are the same chemical element having 2 or more than 2 different types of nuclei, due to difference in the number of neutrons. As a whole copper atom is electrically neutral. 

    The 29 electrons are distributed into shells or orbits. Consequently the first orbit has 2, 2nd orbit has 8 and 3rd orbit has 18 electrons. There is only 1 electron in the outermost orbit of the copper atom. 

  • User experience @ M DASH F dot ORG — optimization issues.

    I was doing some research on optimization of my website. This is what I found.

    Good news: My website is optimized for mobile devices, 15% better than some of the best blogs around the world. That means if you have been accessing my websites on your mobiles, you have been happy about your loading experience.

    Bad news: My website optimization for desktop is 25% worse than these other sites.

    If you have accessed my website from a desktop computer please don’t use curse words.

    I am trying to fix the issues. — Its due to 3rd party rendering issues, like Java script and CSS styling codes.

  • Fundamental types of crystal lattices and their symmetry operations

    3 most important lattice types, the simple cubic (sc), the body centered cubic (bcc) and the face centered cubic (fcc) types

    Fundamental types of crystal lattices and their symmetry operations.

    Topics covered
    a. Types and classes of crystals,

    b. Symmetry operations in crystals

    In this lecture we will follow through our basic knowledge gained in the last lecture. — lecture — I, II, and shed light on the most interesting properties of crystal lattices, viz. their symmetry properties. Based on their properties we will classify them into various types and classes.

    ii. Lattices satisfy additional symmetry operations. But due to the constraint of translational symmetry the total number of symmetry operations that the lattices can satisfy is reduced to a minimum.

    iii. This means in 2-dimensional lattice constructs we have only 5 types of lattices which satisfy additional symmetry operations. In 3-dimensional geometry there are a total of 14 classes of lattices.

    iv. Thus in 3-dimensional lattices the 14 classes of Bravais lattices are categorized into 7 types or systems of fundamental lattices.

    v. The extra symmetry operations are

    various rotations,
    inversion about a space point and
    reflection about a plane passing through a lattice point or
    their possible combinations.

  • Helmholtz theorem in electrodynamics, Gauge transformation.

    The northern light or aurora is an electromagnetic phenomenon, produced due to motion of charged cosmic particles entering earth's magnetic field.

    Electromagnetic theory, lecture — IV

    Topics covered in this lecture

    a. Helmholtz theorem — in electrodynamics

    b. Gauge transformation — of scalar and vector potential in electrodynamics

    c. Coulomb and Lorentz gauge

    All electromagnetic theory lectures of this series, will be found here (

    In our previous lecture — lecture — III, we discussed in quite detail, the problem of electrostatics and magneto-statics.

    We understood how deeply the Helmholtz theorems formulate the entire question of these two branches of electromagnetic phenomena.

    But static problems are not sufficient for any rigorous treatment of the electromagnetic theory.

    We promised in that lecture to study how Helmholtz theorems lend their magical power to understand the most general nature of electromagnetic phenomena.

    In this lecture we will study precisely the applicability of Helmholtz theorems to the problem of electrodynamics and we will see how it leads to a great deal of success in advancing the ability to solve electromagnetic problems of a great variety. 

  • Helmholtz theorem. Scalar and vector potentials

    This image shows the fabulous colors cities wear at night. And it all comes from electromagnetic waves. Our topic today is an attempt at understanding the deeper formal frame work of electromagnetic waves.

    This lecture develops the formalism of electrodynamics in a very methodical way.

    It covers the following topics in detail.

    A. Formalism of electrodynamics — fundamental theorem

    B. Application of Helmholtz theorem — to electrostatics

    C. Application of Helmholtz theorem — to magnetostatics