SCIENTIFIC NOTATION ,its importance , rules and example

  SCIENTIFIC NOTATION

A simple but scientific way to write large or small numbers is to express them in some power of ten

• The Moon is 384000000 metres away from the Earth Distance of the moon from the Earth can also be expressed as 3.84 x10 m. 
• This form of expressing a number is called the standard form or scientific notation. This saves writing down or interpreting large numbers of zeros. Thus In scientific notation a number is expressed as some poOwer of ten multiplied by a number between 1 and 10.
• Scientific notation is useful because it allows us to easily write and make calculations with extremely small and extremely large numbers

• For example, a number 62750 can be

expressed as 62.75x10^2  or 6.275x10^ 3 or 0.6275x10°.

• All these are correct. But the number that has one non-zero digit before the decimal i.e. 6.275x10 preferably be taken as the standard form. Similarly ten standard form of 0.00045 s is 4.5x10 s.

BASE UNITS AND DERIVED UNITS

 BASE UNITS 

 

• The units that  describes  base quantities are called base units.
• Each base quantity has its SI units.

DERIVED UNITS

• The units used to measure derived quantities are called derived units.
•  Derived units are defined in terms of base units and are obtained by multiplying or dividing one or more base units with each other. 
• The unit of area (metre2) and the unit of volume (metre3) are based on the unit of length, which is metre. 
• Thus, The unit of length is the base unit while the unit of area and volume are derived units. 
• Speed is defined as distance covered in unit time; therefore its unit is metre per second. 
• In the same way the unit of density,force, pressure, power etc. can be derived using one or more base units. 

PREFIXES ,ITS IMPORTANCE AND EXAMPLES

 PREFIXES

• Some of the quantities are either very large or very small. For example, 250 000 m, 0.002 W and 0.000 002 g. etc. 
• SI units have the advantage that their multiples and sub-multiples can be expressed in terms of prefixes. 
• Prefixes are the words or letters added before SI units such as kilo, mega, giga and milli

• IMPORTANCE

• The prefixes are useful to express very large or small quantities. For example, divide 20,000 g by 1000 to express it into kilogramme, since kilo represents

EXAMPLES

p	pico	10-12	7 pF = 7 × 10-12 F = 0.000 000 000 007 farads
n	nano	10-9	5 nm = 5 × 10-9 m = 0.000 000 005 meters
μ	micro	10-6	6 μm = 6 × 10-6 m = 0.000 006 meters
m	milli	10-3	5 mm = 5 × 10-3 m = 0.005 meters

Physical Quantities and international system of unit

 

SECOND LECTURE

All possible questions with authentic answers

chapter 1: PHYSICAL QUANTITIES OF MEASUREMENT

All possible questions with authentic answers 

Chapter 1:

 PHYSICAL QUANTITIES OF MEASUREMENT 

Lecture 1 : INTRODUCTION OF PHYSICS