Devender

Let us talk today about how heat conduction occur and why metals are good heat conductors. Heat is energy that can be transferred from hotter to colder body and can be quantified from temperature. But then obvious question is how does this energy transfer takes place? In this discussion, we will only focus on transfer of heat only via conduction and do not take into consideration radiation phenomenon.  At microscopic level, we can quantify heat as motion of atoms. Hotter the body is, more kinetic energy the atoms have (they are shaking vigorously). Now, when you put a hotter body in contact with a colder body, atoms in hotter body which are moving vigorously start to shake the atoms of colder body in contact. This leads to transfer of kinetic energy (vibration of atoms in solids) from hotter body to colder body and thus transfer of heat.  For metals, you also have electrons which are free, so both electrons and atoms will acquire kinetic energy. In fact, both electrons and atom

In the last post , I discussed the difference in bonding between metals and ceramics, and how that is manifested in different properties exhibited by metals and ceramics. Now, let us try to understand why metals actually conduct electricity. The reason again ties down to bonding in metals. Like, I explained here , metals typically exhibit metallic bonding in which all the valence electrons are shared by all the atoms. There is a delocalization of electrons, unlike in covalent and ionic bonds which confine electrons only to neighboring atoms. Now, when an external electric field is applied to metals, these delocalized electrons are easy to move and thus conduct. This simple explanation is basis for Drude Model where Drude actually derives simple quantitative formula for conductivity. This explanation and thus theory is very elementary and is not be able to give correct quantitative numbers for many other properties (heat capacity and seebeck coefficient) of metals. A more detailed th

Recently, I have decided to change the blog to more science oriented. I have started a podcast ( link ) where I have decided to share my understanding of various topics in science. I will try to post 3-4 posts a week on topics related to science. So, for this post let's discuss why certain solids are metals and some ceramics. Solids, in general, can be distinguished as metals, ceramics and polymer. I am keeping the focus on difference between metals and ceramics and not going to discuss polymers in this post. If you checked my last post, matter exist in form of solid due "bonds" which keep atoms together in solid. I discussed three forms of bonds- metallic, covalent and ionic. Metals typically have metallic bonding, which is a delocalized bond where all the valence electrons are shared by each and every atoms. In contrast, covalent and ionic bonds are localized between neighborliness atoms. Atoms in ceramics typically are bound by covalent and ionic bonds. This is the

Why do matter exist as solids? Common forms of matter are solid, liquid and gas. Reason behind existence of matter as any form is governed by interactions between atoms. Electrons surrounding atoms' dictate this interaction. This interaction is what we call as a bond. So, why do atoms interact? Reason for any interaction has to do with decreasing overall energy of the system. There are three possible ways for electrons to interact with electrons of neighboring atoms: - Atom can share electrons with neighboring atom: known as covalent bond - One atom gives away its electron to neighboring atom: known as ionic bond - Atoms share electron with all the whole system, not just surrounding atom: known as metallic bond Like I said before, driving force for atoms interaction is to decrease their energy. Now, this interaction which is termed as bonds is what keep atoms together and forms solid. Solid will fell apart and form gas if there are no bonds. Now, these bonds determine how

After watching this video(http://www.youtube.com/watch?v=2CHcKlIsvAQ&feature=related), I was inspired to actually understand Lokpal better and writing here what all I could find on internet: Difference between Government proposed Lokpal Bill and Jan Lokpal Bill proposed by Arvind Kejriwal et al: Nature of Lokpal:  The government wants Lokpal to be an advisory body, which will only forward its enquiry report to the competent authority for action like CVC is merely an advisory body. Central Government Departments seek CVC’s advice on various corruption cases. However, they are free to accept or reject CVC’s advice then why the heck are the making Lokpall? Just rename CVC to Lokpals. Although CBI can register FIR and file case but it has to take permission from government department before registering an FIR, why would departments give permissions when we all know corruption is from top to bottom in most cases? The Jan Lokpal Bill proposes powers to initiate prosecution after comple

Google had closed the invitation to Google +. Inviting via "adding in circle" is not working also (My friends were unable to invite me via this method). So, here is another method which will lead to invite: Step 1: simply create a status update (on homepage of Google+ find dialog box like "Share what's new"), e.g. “inviting people” and then pasting the Gmail addresses of friends you want to invite into the “add people” box (Next to +1 and Comment links). Step 2: They should then go to the url of google + home page via: https://plus.google.com which will ask them to join. Note: invitees may not receive email so go to url instead. In case you need one, send me your email id on dev@devender.co.cc Also note that, google+ may not work very well in Mozilla so use chrome especially if you are not able to go beyond join page.

  Yesterday, Diesel and LPG's prices were hiked again. This encouraged me to do an analysis for self-satisfaction on whether these price hikes were necessary (rates have been increased 10 times in last one year) or just result of bad administration on PSUs. Now after talking to some friends who are working in oil industries and internet search. a) I found that following is processing cost for oil companies:       74% - Cost of the crude oil       11% - Taxes Please note: This has been reduced yesterday significantly! (Ref: Link1 and Link2 )       10% - Refining costs       5% - Distribution and marketing (Ref: Link3 ) b) Current crude oil cost: Around USD 100/barrel (Ref: Link4 )           So, total cost of processing is: USD 135/barrel (from (a) and (b))           1 oil barrel= 42 gallon and hence 159 litres (approx)           Cost per litre of processed oil: USD 0.85= INR 38.2 c) Now, whether processed oil is petrol/diesel/keronses that depends on demand