## Monday, December 26, 2011

### 75% Students Applied For IIT JEE 2012 Online In The Bombay Zone

For the first time since IIT JEE has gone outline, 75% of the 75,000 applicants in the Bombay zone have applied online. The Bombay zone includes Maharashtra, Goa, Gujarat, parts of Rajasthan and Belgaum in Karnataka. This year, IIT Delhi is organizing IIT JEE which will be held on April 12, 2012.

## Friday, December 23, 2011

### Take a Mock Test for AIEEE online

CBSE has published the facility to practice online for AIEEE.

Click Here to Take the Mock Test now. You should Be using Internet Explorer 7 or higher to use the facility.

## Saturday, December 17, 2011

### Motion of proton in a magnetic field

We are viewing a proton from a height downwards.The proton is moving horizontally along a circular path in a uniform magnetic field directed vertically upwards.Why its direction of motion will be clockwise?

## Friday, December 16, 2011

### CLASS XI PHYSICS IMPORTANT QUESTIONS

3 MARKS:
1) DISTINGUISH BETWEEN FUNDAMENTAL UNITS AND DERIVED UNITS.
2) WHAT ARE THE TWO TYPES OF COLLISION? EXPLAIN THEM.
3) STATE NEWTONS FIRST LAW OF MOTION.
4) TWO EQUAL FORCES ARE ACTING AT A PIONT WITH AN ANGLE OF 60 BETWEEN THEM. IF THE RESULTANT FORCE IS EQUAL TO 20√3N. FIND THE MAGNITUDE OF EACH FORCE.
5) WHAT ARE THE DIFFERENT TYPES OF EQUILIBIRIUM.
6) STATE THE UNIVERSAL LAW OF GRAVITATION.
7) DEFINE GRAVITATIONAL POTENTIAL.
8) WHAT IS REYNOLD’S NUMBER?
9) WHAT IS SURFACE TENTION?
10) DEFINE SIMPLE HARMONIC MOTION.
11) WHAT ARE DEGREES OF FREEDOM?
12) DEFINE SOLAR CONSTANT.

13) DEFINE POWER OF A LENS. WHAT ITS UNIT?
14) STATE TANGENT LAW.
15) WHAT IS THE DISTANE TRAVELLED BY SOUND IN AIR WHEN A TUNING FORK OF FREQUENCY 256HZ COMPLETES 25 VIBRATIONS? (THE SPEED OF SOUND IN AIR IS 343MS-I)

5 MARK:

1. WRITE ANY 5 RULES AND CONVENTIONS OF WRITING SI UNITS.

2. THE HORIZONTAL RANGE OF A PROJECTILE ID 4√3 TIMES ITS MAXIMUM HEIGHT. FIND THE ANGLE OF PROJECTION.

3. STATE THE LAW OF CONSERVATION OF ANGULAR MOMENTEM AND EXPLAIN IT WITH AN EXAMPLE.

4. STATE KEPLER’S LAW OF PLENTARY MOTION.

5. GIVE THE GRAPHICAL REPRESENTATION OF i)DISPLACEMENT ii) VELOCITY iii) ACCELERATION OF A PARTICLE EXUCUTING SHM. MENTION THE DIFFERENCES BETWEEN THEM.

6. What are the characteristics of progressive waves?

7. List out any 5 postulates of kinetic theory of gases.

10 MARK:

1. State and prove parallelogram law of vectors and discuss the special cases.

2. State and prove bernoulli’s theorem.

3. Derive Meyer’s relation.

4. Describe the working of angstrom pyrheliometer with diagram. (NOT FOR CBSE)

### Interesting News in Physics

Dancing in the quantum world - physicsworld.com

A new project known as "Danceroom Spectroscopy" represents a genuine fusion of art and science, resulting in an impressive visual art show that is driven by real physical laws.

The project's mastermind is David Glowacki, a researcher at the University of Bristol in the UK. In this special video report, Glowacki talks to Physics World journalist James Dacey about his stimulus for the project and how the technology involved was inspired by some of the concepts from his research in theoretical chemistry. Glowacki describes how the project came about through a conversation with a friend about making music via motion. "What we quickly found out was that the idea had been done to death, so I came up with a more interesting way of attacking that problem," he explains.

### Worthy Links for those interested in recent develpoments in Physics #1

HANDS-ON CERN -- English version

Hands-on-CERN (HoC) is an educational project at the scientific frontier of physics. It is aimed at teachers and high school students studying natural sciences. The purpose of this project/course is to increase understanding of the most fundamental processes inside matter, and to explain modern research about particle collisions.

NASA: Climate change may bring big ecosystem changes

By 2100, global climate change will modify plant communities covering almost half of Earth's land surface and will drive the conversion of nearly 40 percent of land-based ecosystems from one major ecological community type - such as forest, grassland or tundra - toward another, according to a new NASA and university computer modeling study.

Physicists Anxiously Await News of the ‘God Particle’ - NYTimes.com

High noon is approaching for the biggest manhunt in the history of physics. At 8 a.m. Eastern time on Tuesday morning, scientists from CERN, the European Center for Nuclear Research, are scheduled to give a progress report on the search for the Higgs boson — infamously known as the “God particle” — whose discovery would vindicate the modern theory of how elementary particles get mass.

## Thursday, December 15, 2011

### Candle flame in microgravity

What is the cause of the shape of candle flame? How will it be affected by gravity? What will be the shape  of candle flame in the absence of gravity?

Find below the predictions by some plustwo students - Athul, Ganesh and Harikrishnan.

### Buoyancy in microgravity

What happens to Buoyancy in outer Space? See the assumptions, hypothesis and prediction by plustwo students keenly interested in Physics and astronomy.

## Sunday, December 11, 2011

### PhysicsHomeWork.Net now points to AskPhysics

PhysicsHomeWork.Net was a website started to help the students worldwide in Physics. . The site is now acquired by www.askphysics.com

The earlier site will now be redirected to askphysics.com and anyone can now post Home Work questions in Physics too at askphysics.com

Physics homework help provides problems, solutions, free quizzes. Visit now for assignment, physics assignment, physics homework, physics homework help, physics help online, physics assistance, physics assignment help, physics writing service, physics solver, physics helper, do my physics, help me with my physics, buy physics assignment, order physics project, physics solutions, physics problems. It provides students with professional physics homework help and physics assignment assistance.

## Friday, December 2, 2011

### SEMICONDUCTOR DEVICES–CLASS 12 PHYSICS QUESTION BANK

1. Draw a circuit diagram of OR gate.

2. What is a logic gate?

3. What types of charge-carriers are there in a n-type semi conductor?

4. Give the logical symbol of an AND gate. Mark the inputs and outputs.

5. Draw the logic symbol for a NAND gate.

6. Which biasing will make the resistance of p-n junction high?

7. Write the truth table for OR gate.

8. What is the change in the collector current, in a transistor of a.c. current gain 150, for a 100µA change in its base current?

9. When the voltage drop across a p-n junction diode is increased from 0.65V to 0.70V, the change in the diode current is 5mA. What is the dynamic resistance of the diode?

10. How does conductivity of a semiconductor change with rise in its temperature?

### Class 12 Physics : Electrostatics Revision Test

Max marks:50 Time:2hrs

1. A glass rod rubbed with silk acquires a charge of 6x10-12 C. Calculate the number of electrons it has gained or lost. (1)
2. If the magnitude of each charge becomes doubled, the separation between them is halved and the system of charges kept in a medium of=3 Calculate the force between them. (1)
3. If two equal charges separated by a distance of 2m in air medium experiences a force of 0.9x1010 C, Calculate the magnitude of each charge. (1)
4. Electric field intensity is 400Vm-1 at a distance of 2 m from a point charge. At what distance it will become 100 Vm-1? (1)
5. What will be the force experienced by a particle of charge 2µC placed in an electric field of 10kVm-1? (1)
6. What is the work done by moving 400μF charge between two points separated by a distance of 27 cm on an equipotential surface? (1)
7. Calculate the number of electric lines of force from a charge 1.7708X10-6 C in air medium? (1)
8. Two protons ‘A’ and ‘B’ are placed between two parallel plates having a potential difference ‘V’ as shown in the figure. Will these protons experience equal or unequal force? (1)
9. Draw an equipotential surface for a point charge q> 0(1)
10. The capacitance of a parallel plate capacitor is ‘C’. If 15 such capacitors are connected in series and then in parallel, what is the ratio of effective capacitance of first case to the second? (1)
11. What is electric polarization ,polar and non polar molecules?( 2)
12. 2) Define electrostatic induction and corona discharge. ( 2)
13. Calculate the ratio of force experienced by a proton to that of the electron placed in an electric field of 4KVm-1. ( 2)
14. If an electrician has three capacitors of capacitances 4µF, 7µF& 12µF. How should he connect them, So that the effective capacitance will be 10µF? ( 2)
15. Define the SI unit of potential difference and charge. ( 2)
16. Two charges of 20µC and -20µC are placed 20 cm apart at points A and B respectively. Compute the electric field strength at point C, 20 cm away from both A and B.(3)
17. Three capacitors of capacitances 4µF, 6µF and 8µF are connected parallel to each other and the combination is connected across a battery of 25V. Calculate the charges present on each capacitor and the total charge flows from the source. (3)
18. Derive an expression for the torque experienced by a dipole in an external electric field. (3)
19. Obtain an expression for the capacitance of a parallel plate capacitor. (3)
20. Derive the relation E= (3)
21. Derive an expression for the potential at a point due to dipole. Write the special cases also.(5)
22. Derive an expression for ‘E’ at a point on the axial line of the dipole. (5)
23. Explain with a neat diagram the principle, construction and working of a Van de Graff generator. (5)

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