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What are plasmons?

A plasmon is a quantum of plasma oscillation, just like photon is a quantum of light radiation.

Plasmon is a quasiparticle resulting from the quantization of plasma oscillations.

Plasmons play a large role in the optical properties of metals. Light of frequency below the plasma frequency is reflected, because the electrons in the metal screen the electric field of the light. Light of frequency above the plasma frequency is transmitted, because the electrons cannot respond fast enough to screen it. In most metals, the plasma frequency is in the ultraviolet, making them shiny (reflective) in the visible range.

[gview file=”http://www.photonics.ethz.ch/fileadmin/user_upload/optics/Courses/NanoOptics/plasmons.pdf”]

Surface plasmons

Surface plasmons are those plasmons that are confined to surfaces and that interact strongly with light resulting in a polariton

Read more at http://en.wikipedia.org/wiki/Surface_plasmon

[gview file=”http://www.optics.rochester.edu/workgroups/novotny/courses/OPT463/plasmonss.pdf”]

Nuclear Fission and Fusion – A Facebook conversation

Find below a conversation between Master Deepak, PUC student and Mr. Mathew Abraham, Physics teacher.

Deepak asked: “nuclear fusion or fission in which of these energy released is more and why?”


Energy released per fission is more than energy released per fusion. But energy released per unit mass during fusion is very much greater than energy released per unit mass during fission


But why energy released is more


The fission of a U-235 releases about 200 MeV of energy
whereas the fusion of 4H to form He releases only about  20 MeV
But, the 200 MeV is obtained from 236 amu
and the 20 MeV is obtained from just 4 amu


Then why dont we use nuclear fusion as source of energy and electricity



Nuclear fusion requires very high temperature to start. It is difficult to maintain such a huge temperature (of the order of million degrees).

Tokamak magnetic field and plasma current.
Tokamak magnetic field and plasma current. (Photo credit: Wikipedia)

Research is going on to construct nuclear fusion reactor

The international prototype is named tokamak
In that the nuclear fusion is carried out in plasma state held at high temperature confined in magnetic field produced by huge torroidal solenoids


What is Pseudo force?

What is Pseudo force? Asked Rahul Answer: The word pseudo means false. Remmeber pseudopodia, the false legs of amoeba.(Also called fictitious force,or phantom force) An additional force due to nonuniform relative motion of two reference frames is called a pseudo-force. A pseudoforce does not arise from any physical interaction between two objects, but rather from the acceleration a of the non-inertial reference frame itself. A fictitious force on an object arises when the frame of reference used to describe the object’s motion is accelerating compared to a non-accelerating frame.

English: Forces in accelerating car
Forces in accelerating car (Photo credit: Wikipedia)

[gview file=”http://www.askphysics.com/wp-content/uploads/2013/09/pseudoforce.pdf”]

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September 2013

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