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## Why don’t the birds perching on high power electric lines do not get an electric shock?

What is an electric shock? It’s a a sudden discharge of electricity through a part of the body.

For a sudden discharge of electricity, the prime need is a potential difference. When the bird perches on an electric line, it is at a high potential, but it is not subjected to a high potential difference between two parts of its body and hence it does not get a shock. The entire body is raised to the same potential as that of the electric line.

So, the electric potential difference is the VILLAIN.

## The Exams are near! Start Smart Preparation (Not just hard work!)

Exam are near. CBSE Exams starts from 1 March. The candidates need to be on toes to score well.
Smart work is better than hardwork. Just burning midnight oil alone won’t work.
Nobody plans to fail, but fails to plan. A failure to plan well may result in ultimate failure. So planning the work based on your target is the essential step to start with. So, fix your targets depending upon your abilities.

As per the current trend, a student can get 100% score in any subject – even in languages and subjects under humanities.

Don’t worry even if you were scoring low marks throughout the year. Start now!
Have a look at the syllabus and previous question papers. Understand the pattern of question paper. Make a plan to score the MAXIMUM. Take guidance from your teachers (or the experts in the field).
Make a time table as per the guidance and stick to the time table.

Work smart and score well.
All the best!

How many time constant will be elapsed before the power delivered to the battery drops to half of its maximum value? Asked Mrityunjoy

Nucleus of an atom consists of neutral neutrons and positively charged protrons… then why do protons not attract neutrons and share charges with them? (+ve charges are supposed to attract neutral & -ve charges,aren’t they? and once they are in contact they share charges!) Asked sree

## How was your CBSE Class 12 Physics Exam 2013?

How was the Physics Exam today?

Were there questions beyond your comprehension?

Were there questions out of Syllabus?

## Electrostatics – One mark and two marks questions for practice

So far we were concentrating on 3 and five marks questions only. Now I think that concentrating on one and two marks questions will further increase the chance of scoring better.

It’s true that just by concentrating on the three marks and five marks questions one can easily score greater than 60% marks. But it is not enough. When you CAN SCORE MORE why should you compromise for less?

Often the one and two marks questions are tricky and twisted. But, when the questions are tricky, there is a greater chance to score. All you need is to apply your commonsense (often complained that it is not so common!) and logical reasoning. The basic facts remain the same however the question maker twist them. So, believe that whatever question asked are based on what you have learnt. But beware!, whatever conclusions you draw must satisfy your commonsense as well as that of the examiner.

So, here are a collection of one mark and two marks questions from ELECTROSTATICS. The straight – forward questions are intentionally avoided.

## A Problem from Optics – Reflection of light

Convex and concave mirrors have same radii of curvature R. The distance between the mirrors is 2R. At what point on the common optical axis of the mirrors should a point source of light A be placed for the rays to converge at the point A after being reflected first on the convex and then on the concave mirror?