## Tuesday, June 29, 2010

### What are the differences between space and vacuum?

Space relates to the three dimensional (or four dimensional or even more dimensional) region which is necessary for any object to occupy.

Vacuum denotes the absence of any matter.

### What is the force opposing gravity of earth or simply gravitational force?(We can use this to invent magic broomstick like in harry potter movies!!!..)

Gravity is the weakest force in nature but depends on the mass of the particles involved. If you use any other force (Any of the three other fundamental forces or the derivatives of them) it may be possible to defy the gravity.

We do such problems like

What amount of equal charge be given to earth and moon so that the effect of gravity is nullified. If you are in an attempt to invent a device which actively defies gravity or cancels the effect of gravity, I would suggest to go ahead.

All the best.

### Why the ray of light passing through optical center of a lens passes undeviated while when it passes through other points on the interface of the lens, it gets refracted?

Deviation is the change in direction of the ray while passing through the lens. The middle portion of the lens is comparatively flat and there is a point on the principal axis and inside the sphere through which all the undeviated rays pass.

“Undeviated” doesn’t mean that there is no refraction. When we say that there is no deviation, we only mean that the incident ray and the emergent ray are parallel to each other. For thin lenses, the refraction inside the lens is negligible and therefore we represent the ray passing through the optic centre as a straight line. But in the case of a thick lens, we cannot do so.

(See the diagram)

### Why the ray of light passing through the centre of curvature of a concave mirror behave as normal while it doesn’t behave as normal when it passes through other points on the principal axis?

Remember that a concave mirror forms part of a hollow sphere.

Any line joining the centre of the sphere (the centre of curvature of the mirror) and any point on the mirror will be normal to the reflecting surface of the mirror.

Therefore A ray of light passing through the principal axis will be normal to the surface as it is passing through the centre of curvature of the mirror.

• The principal axis of a mirror is the straight line passing through the centre of curvature and pole

### When several transparent materials are kept above each other, the resultant behaves like an opaque object.Why?What’s the Optics behind it?

When light falls on a object, three things happen -

• A part of the light is absorbed
• Another part is reflected ad
• The remaining part is transmitted.

A transparent medium transmits most of the light incident on it. However, it absorbs a small part as well as reflect a small part.

Therefore, when a number of transparent sheets are stacked, the amount of light absorbed will be considerably large and the arrangement tends to be opaque.

### Why does no electric current flow through vacuum?

Electric current is the flow of charges. In vacuum, there is no material medium to provide the free charges to move on application of a potential difference. In other words, vacuum is the best insulator.

However, if sufficiently high potential difference is applied to setup a strong electric field, charges can be transferred through vacuum. (Remember the working of vacuum tubes / electronic valves)

(Discussion expected from students, teachers and visitors)

### What is a Parallelopiped (Also named Parallelepiped)

A parallelopiped or parallelepiped is a three-dimensional figure formed by six parallelograms. (See figure)

### Questions received from a curious UG student

I have several doubts in physics.Would you like to answer me please?The following are the doubtful questions I have -
2.What is a 'parallelopiped'?Is it a 3-dimensional parallelogram?
3.Why does no electric current flow through vacuum?
4.When several transparent materials are kept above each other, the resultant behaves like an opaque object.Why?What's the Optics  behind it?
5.Why the ray of light passing through the centre of curvature of a concave mirror behave as normal while it doesn't behave as normal when it passes through other points on the principal axis?
6.Why the ray of light passing through optical center of a lens passes undeviated while when it passes through other points on the interface of the lens, it gets refracted?
7.What is the force opposing gravity of earth or simply gravitational force?(We can use this to invent magic broomstick like in harry potter movies!!!..)
8.(i)A 3-dimensional space consists of how many planes?(My supposition is Infinite)
(ii)A hyperspace consists of how many planes?
9.Why is the interface of concave/convex lens inside the the lens while it is on the boundary of a rectangular glass slab?
10.Does the flow of all sub-atomic/universal particles constitute electric current?If not, why? If yes,  then how can there be charges of two types i.e. +ve and -ve?
11.From where does charges arise in electrons and protons?
12.What is the difference between viscosity and elasticity?
13.What are the differences between space and vacuum?

## Monday, June 28, 2010

### Australia asked to spare existing Indian students from new law

New Delhi: Around 15,000 Indian students in Australia could be forced to return home under a revised skills list that is set to become the mandate for visas and permanent residency to that country from July 1. Minister for Overseas Indian Affairs Vayalar Ravi has urged Canberra to exempt existing st...

### Scope and Excitement of Physics

I have decided to write this short article because Many students asked me to give them an easy way to Write a note on the Scope and Excitement of Physics

## Scope of Physics

Scope relates to the field of study in Physics. That is what all things are included in the study of Physics.

When discussing Physics, it would be better to ask what not is included. Physics discusses anything in the universe. Physics is the study of matter and energy with which the entire universe is made up of.

To Quote from the NCERT Text
"The scope of physics is truly vast. It covers a tremendous range of magnitude of physical quantities like length, mass, time, energy, etc. At one end, it studies phenomena at the very small scale of length (10-14 m or even less) involving electrons, protons, etc.; at the other end, it deals with astronomical phenomena at the scale of galaxies or even the entire universe whose extent is of the order of 1026 m. The two length scales differ by a factor of 1040 or even more. The range of time scales canbe obtained by dividing the length scales by the speed of light : 10–22 s to 1018 s. The range of masses goes from, say, 10–30 kg (mass of an electron) to 1055 kg (mass of known observable universe). Terrestrial phenomena lie somewhere in the middle of this range."

In Physics, we study from extremely small  to  extremely large. Physics discusses the beginning of the universe and the various phenomena occuring recurrently in the universe. Wherever there is matter and energy, there is Physics.

## Excitement of Physics

The NCERT Book says,
"Physics is exciting in many ways. To some people the excitement comes from the elegance and universality of its basic theories, from the fact that a few basic concepts and laws can explain phenomena covering a large range of magnitude
of physical quantities. To some others, the challenge in carrying out imaginative new experiments to unlock the secrets of nature, to verify or refute theories, is thrilling. Applied physics is equally demanding. Application and exploitation of physical laws to make useful devices is the most interesting and exciting part and requires great ingenuity and persistence of effort."

Physics is exciting because

• It trains us in problem solving

• It helps us to have an analytical outlook

• To observe rather than see things

• Everything is explained on the basis of the cause effect relationship, which helps us think logically and decide rationally

• Whether or not, a students of plus two continue to learn Physics, the basic problem solving skill he has acquired during the PlusTwo Physics course will remain with him and will be constantly helping him in all walks of life.

## Saturday, June 26, 2010

### Online Assignments and Project Write up Submission site

Students of Kendriya Vidyalaya Pattom now post assignments and project write ups online at http://kvphysics.blogspot.com

A good initiative in reducing Paper Consumption and thereby reducing deforestation.

The teacher is also benefited as the project submitted are always available for reference.

How it works?

• The teacher starts a blog for the assignment announcement and submission

• Invites students of his class as contributors.

• The students accept the invitation and starts posting their entries as blogs

• Teacher reviews their entries and gives suggestions as comments.

• The students update their entries and resubmit and the cycle is repeated until the desired level of quality and quantity is reached.

• Grades are assigned to the submissions according to the quality of the submitted project.

## Friday, June 25, 2010

### "The Strangest Man" Of Science

Award-winning writer and physicist Graham Farmelo talks with podcast host Steve Mirsky (picture at left) about "The Strangest Man," Farmelo's biography of Nobel Prize-winning theoretical physicist Paul Dirac. [More]

Steve Mirsky - Nobel Prize - Theoretical physics - The Strangest Man: The Hidden Life of Paul Dirac Quantum Genius. Graham Farmelo - Paul Dirac

## Thursday, June 24, 2010

### UN announces environment education programme for students

New Delhi: In order to spread awareness about the environment and develop young leaders in the field, the United Nations on Thursday announced a global environment educational programme for students.The Bayer Young Environmental Envoy Programme (BYEEP) organized by healthcare company Bayer and the U...

## Monday, June 21, 2010

### Chinese parents oppose children's internet use

Beijing: Many parents in China are not in favor of their children using the internet and a majority of them worry that surfing the net could adversely affect children's studies, a study has said.Around 42.6 percent of parents surveyed "strongly oppose their children's use of internet" or "relatively...

### Physics 10 – Lecture 06: Radioactivity II

Physics 10: Physics for Future Presidents. Spring 2006. Professor Richard A. Muller. The most interesting and important topics in physics, stressing conceptual understanding rather than math, with applications to current events. Topics covered may vary and may include energy and conservation, radioactivity, nuclear physics, the Theory of Relativity, lasers, explosions, earthquakes, superconductors, and quantum physics. [courses] [physics10] [spring2006] Credits: lecturer:Professor Richard A. Muller, producers:Educational Technology Services
Video Rating: 4 / 5

### Introducing ASKPHYSICS.COM – A Physics Discussion Site for students

AskPhysics.com is a website for enabling students as well as others to ask questions and discuss Physics. The site is in Bulletin Board Style and the questions and answers will come in threaded form. Ask Physics has just started and is expected to be a big hit. The clean interface and simplicity adds to its elegance.

## Sunday, June 20, 2010

### Introduction To Fourier Optics

This renowned text applies the powerful mathematical methods of fourier analysis to the analysis and synthesis of optical systems. These ubiquitous mathematical tools provide unique insights into the capabilities and limitations of optical systems in both imaging and information processing and lead to many fascinating applications, including the field of holography.

Rating: (out of 10 reviews)

List Price: \$ 158.75

Price: \$ 84.32

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## Saturday, June 19, 2010

### Kids with home computers score lower marks

Washington: While education activists worldwide seek to bridge the "digital divide" by ensuring universal access to home computers, students are found to post lower scores once these technologies arrive at home, says a study.Jacob Vigdor and Helen Ladd, professors at the Duke University's Sanford Sc...

### Faster-than-light electric currents could explain pulsars

Claiming that something can move faster than light is a good conversation-stopper in physics. People edge away from you in cocktail parties; friends never return phone calls. You just don't mess with Albert Einstein. So when I saw a press conference at the American Astronomical meeting this past January on faster-than-light phenomena in the cosmos, my first reaction was to say, Terribly sorry, but I really have to go now. Astrophysicists have been speaking of FTL motion for years, but it was always just a trick of the light that lent the impression of warp speed, a technicality of wave motion, or an exotic consequence of the expansion of the universe. These researchers were claiming a very different sort of trick. Dubious though I was, I put their press release in my "needs more thought" folder and today finally got around to taking a closer look. And what I've found is utterly fascinating.

[break]

[More]

Albert Einstein - Physics - Faster-than-light - Metric expansion of space - History

## Friday, June 18, 2010

### UN, Hamas compete over summer camps for Gaza children

Gaza: The UN and the Hamas group are up in arms against each other in organizing summer camps for children in the Gaza strip and over 600 camps with more than 5,000 children have already been set up.The UN Relief and Work Agency (UNRWA), which inaugurated this week summer-camps in the Gaza beachside...

## Thursday, June 17, 2010

### 9/11 Nano thermite used to demolish all three World Trade Center buildings

The Open Chemical Physics Journal www.bentham-open.org BREAKING NEWS – Chemist talks about the findings of explosives in dust from World Trade Center. (English subtitles) www.youtube.com Niels Harrit explain nano thermite on national TV2 7th of April 2009 – English Subtitles www.youtube.com
Video Rating: 3 / 5

The Journal of Chemical Physics’s Editor, Marsha I. Lester, discusses the journal’s new Spotlight Collections. The Journal of Chemical Physics has created a new Perspectives section, featuring invited papers on topics currently generating a great deal of interest in the research community. JCP Spotlight Collections, which will be home to the collected perspectives, along with the seminal articles they reference, provide a comprehensive look at the history of the field and where it is headed. Perspectives will be a regular feature of the journal and freely available to the community. We hope these collections will be a useful research tool, as well as a valuable resource for those interested in learning more about the broad range of topics in Chemical Physics.
Video Rating: 0 / 5

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## Wednesday, June 16, 2010

### Rosetta’s Blind Date with Asteroid Lutetia

ESA’s comet-chaser Rosetta is heading for a blind date with asteroid Lutetia. Rosetta does not yet know what Lutetia looks like but beautiful or otherwise the two will meet on 10 July.

Like many first dates, Rosetta will meet Lutetia on a Saturday night, flying to within 3200 km of the space rock. Rosetta started taking navigational sightings of Lutetia at the end of May so that ground controllers can determine any course corrections required to achieve their intended flyby distance.

[...]

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## Tuesday, June 15, 2010

### Novel bioplastic to boost performance of bionic devices

Sydney: A young researcher has developed conductive bioplastics that will boost the performance of bionic devices such as the cochlear ear and the proposed bionic eye."Our plastics will lead to smaller devices that use safer smaller currents and that encourage nerve interaction," says biomedical eng...

## Monday, June 14, 2010

### 3E super partnership between India, Canada urged

Toronto: A leading educationist here has called for a 3E "super partnership" - involving energy, entrepreneurship and education - between India and Canada in mutual interest. Indira Samarasekera, who is the president of the University of Alberta, said India and Canada can forge this super partn...

### 1st and 2nd Laws of Thermodynamics

My teacher asked me to put this up, but everything else on my Account is Star Wars, so this had to be too. Star Wars is owned by George Lucas Song written and performed by Michael Flanders and Donald Swan Jokes by Science teachers

A pair of blasters explain the first and second laws of thermodynamics in the best possible way: by setting Arachnos on fire.

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## Sunday, June 13, 2010

### Let's try to Understand the Theory of Relativity

 Einstein's theory of special relativity includes electricity and magnetism in a simple, logical extension of the relativity of Galileo and Newton. Its conclusions, including time dilation, length contraction, and E=mc2 have changed profoundly our ideas of time and space, matter and energy.Find more at http://www.phys.unsw.edu.au/einsteinlight/The link will open in a new window.

Find below some Physics Sites for high School and Plus Two Students. Please note that the links will open in a new window.

http://www.ndrs.org/physicsonline/index.htm

http://www.physicsclassroom.com/

http://www.splung.com/

http://ocw.mit.edu/high-school/physics/

http://www.phys.unsw.edu.au/~jw/FAQ.html

## Physics for scientists and engineers, Chapter 23 Solutions

The link will open in a new window

You can also start discussions or take part in already running discussions after joining the group http://groups.google.com/group/plustwophysics/

## Friday, June 11, 2010

### Chinese students puzzled at bizarre essay test

Beijing: "Would cats take the trouble of catching rats when they can have easy access to fish?" "Looking up to the starry skies and keeping down-to-earth" or "The change of light and shadow in one's life." Students in China have been left puzzled by these essay questions in the national entrance exa...

### We are retiring Physics Classroom soon.

We are planning of retiring "Physics Classroom" soon.

The Plustwo Physics Blog will continue. You will get all the contents already published in Physics classroom from within the Blog Section.

[ad#bidvertiser 336]PlusTwo Physics Blog Provides Physics Sample Papers, Lesson Notes arranged module wise, Previous Physics Question Papers of different Boards (CBSE, ICSE/ISC, SSLC/HSC etc), Solutions to problems and doubts received via email, Question Bank, Physics Guess Papers, Physics Videos, Latest Physics related news from all over the world updated daily and many more.
The students and visitors can interact with Physics Master via Comments, email or the ASK A QUESTION section.

### Important !! Wait till the site fully loads ...

All the links will work correctly only if you click the links after the site is completely loaded. So it is requested that the visitors to be patient till the page is loaded completely

## Thursday, June 10, 2010

### University fees set to rise in Britain

London: British and international students are likely to pay higher tuition fees as the new coalition government is set to squeeze spending in the higher education sector and university managements are ready to hike the fees.The axe is expected to fall first on home and European Union students whose...

## Wednesday, June 9, 2010

### Peruvian poet wins Chile's Neruda Prize

Santiago: Peruvian poet Antonio Cisneros has been named the winner of the 2010 Pablo Neruda Ibero-American Poetry Prize.The Chilean government confers the prize in honor of the country's late Nobel laureate. Chilean Culture Minister Luciano Cruz-Coke chaired the jury. Chilean President Sebastian Pin...

## Tuesday, June 8, 2010

### Secondhand Smoke Ups Risk of Mental Illness

Healthy adults exposed to secondhand smoke appear to be at higher risk of suffering psychological distress and future psychiatric illness requiring hospitalization, according to a major Scottish population study.

## Monday, June 7, 2010

### Electrostatics Notes – Module II (Electric field, Dipole, Gauss Theorem)

Click the Link below to download Electrostatics Notes - Module II (Electric field, Dipole, Gauss Theorem and Applications)