Physics Spl

Hi Uttam,
First of all, wishing you a very best of luck for your Class 12 board exams and for your future.
Well, coming to the question, you are asking how you should prepare Physics for your boards (As I assume). In this answer, I will try my best to give you a good way to succeed in your boards.
Physics, is, was and always will be a big subject to all Science students appearing for board exams. The main reason for this is that the topic you have to study is a bit vast, and you need a good strategy to nail it.
1. Books
As far as your Board exams are considered, the CBSE prescribes you two books (NCERT Textbook) NCERT Exemplar Textbook though the board, and we all know that these two books won't cater to all needs of all type of students, this is what CBSE has prescribed. For you board exams, you should be well enough in getting your concepts very well. In Recent years, CBSE has started to ask questions in a twisted manner, that makes the student to think twice before answer, so my best bet would be to use SL Arora book as a reference book for your boards. The book is very good in providing you in depth understanding of concepts due to its student friendly presentation.
2. How to prepare from books
Simply reading texts and your notes are not going to fetch you a centum in your boards. There needs to be a clever strategy to be made sure that you cover all the In text questions and Exercise questions that are given at the end of each chapter. Study all the graphs that are given alongside with the text portion. Be very vigilant in writing laws- Make sure that you dont alter the meaning of laws that were predefined by others, Do numerical questions sincerely. For this, NCERT Exemplar book is really going to help you out. This book has a higher level of problems which will help you to brush up your knowledge. Also, it will help you a lot, if you are an IIT aspirant. Be sincere in your studies. Never cheat yourselves that you know everything from textbook. Once you finish this, go and try solving old question paper questions. Analyze yourselves on how you perform while solving these questions. This helps you to find where you lag or where you excel.
Keep practicing.
All the best.

Hi Rohith,
First of all, you have to study advanced physics and mathematics. Now, you can either sit in competitive exams and get a good rank, or pursue higher education in reputed institutes until you get a Ph.D. Your current course won't be an obstacle. By first year, I think you mean intermediate or class XI. If yes, then it's perfect. If you mean B.Sc., then it's still cool, you have a lot of time left.
Having a creative mind and good grip on subjects of astrophysics, particle physics, quantum mechanics, cosmology, and basic Newtonian physics will be very helpful. For that, I would recommend reading books on the subject. I'm going to give a recommendation list in the end.
Don't think that only good numbers, good ranks, or tags of top institutes can make you an astrophysicist. There are many research centres and organisations, even ISRO, who don't take these criteria too seriously.
Believe in yourself. If you have the brain of an astrophysicist, you will be recognised just with good knowledge, good percentage, and interest. No need for excellent marks.
It's a very technical field, and I'm myself very interested in this, so I would recommend having a good grasp on interesting topics like string framework, spacetime, nothingness, symmetry, inflation, entropy, etc. After this, make sure you have enough qualifications and marks. You'll have to pay attention to supplementary subjects like maths because they can dampen your overall prospects.
Recommended books:
The Fabric of the Cosmos by Brian Greene: must read, general-level, would explain most complicated topics with the least hassle like about time, quantum mechanics, inflation, etc.
Stardust by John Gribbin: a very beautiful book that's more literature than Science.
A Brief History of Time by Stephen Hawkins: somewhat advanced but needed once you're serious about being an astrophysicist.
You might also try The Theory of Everything and An Elegant Universe.
I hope this helps.
All the best.

Hi Chanchal,
Well, first of all, you can't get something for nothing. The work electricity can do is measured in watts. Light a bulb, run a microwave, a hair dryer, whatever. And watts are calculated using Ohms Law:
E (volts) times I (current) = P (power, in watts). So, for a given amount of power, if E goes up, I must go down.
Transformers pass current by the primary generating a magnetic fiel, which induces a current and voltage in the secondary. You can step up, down, or neither voltage.This is accomplished by having a different number of windings on the primary and secondary coils. If the number of turns on the coil in both primary and secondary coils is the same , the voltage and current on both sides will be the same, minus the loss incurred across the transformer. Commercial transformers are very efficient, upwards of 95%.
If the windings on the secondary are twice as many as on the primary, the voltage will double, the current will halve.
I hope it's clear.
All the best.