Dear friends
Now we study about the dimensional analysis, we have already in previous two articles that how we have to plan for getting maximum marks with the least effort in these balance days .
As units and dimensions is the first chapter we start from there itself . now in this chapter you should know how to find dimensions from any given formula, second thing which is more important you should be able to compile the formula based on dimensional analysis . I would personally advise you some of the dimensions , which you can otherwise also find but will consume sometime, secondary these are asked in examination . so those dimensions are coefficient of viscosity, universal gravitational constant, Planck’s Constant, surface tension and also of elasticity . secondly the dimensions of you should know electrical and magnetic constants, namely permittivity . and permeability. 20 electrical constants and magnetic constants will help you in getting the questions in lesser time, that is very much required in your medical examination .
After these basics dimensions, second type of questions which are important are off finding the errors and its types . one type of errors are defined theoretical errors, which you can easily recognised by reading type of error. They are termed as instrumental error. then comes the part of calculating errors, by addition or subtraction multiplication and division. You should understand that multiplication and division follow a set of rules, while addition or subtraction follow different set of rules. In addition and subtraction absolute error straightway add up, while in multiplication and division relative errors are added up. After this we will have to use combination of multiplication and division as required by question.
After the errors, we should understand the concept of significant figures in Physics . There are certain fixed set off rules that determine the final value .
All the non-zero digits are significant.
- All the zeros between two non-zero digits are significant, no matter where the decimal point is, if at all.
- If the number is less than 1, the zero(s) on the right of decimal point but to the left of the first non-zero digit are not significant. [In 0.002308, the underlined zeroes are not significant].
- The terminal or trailing zero(s) in a number without a decimal point are not significant. [Thus 123 m = 12300 cm = 123000 mm has three significant figures, the trailing zero(s) being not significant.] However, you can also see the next observation.
- The trailing zero(s) in a number with a decimal point are significant.[The numbers 3.500 or 0.06900 have foursignificant figures each.]
Also addition and subtraction one set of rules followed is followed and in multiplication and division other set is followed. In addition or subtraction we will give the final answer in as many significant numbers as are least in among the two numbers, why in multiplication and division the final answer is written in least significant figures among the numbers which are multiplied or divided .
In multiplication or division, the final result should retain as many significant figures as are there in the original number with the least significant figures
In addition or subtraction, the final result should retain as many decimal places as are there in the number with the least decimal place
The rule by convention is that the preceding digit is raised by 1 if the insignificant digit to be dropped (the underlined digit in this case) is more than 5, and is left unchanged if the latter is less than 5. But what if the number in which the insignificant digit is 5. Here, the convention is that if the preceding digit is even, the insignificant digit is simply dropped and, if it is odd, the preceding digit is raised by 1.
We now take questions of NEET 2019