These notes are provided by studifysuccess
CLASS : 11 PHYSICS
Chapter 1
UNITS AND MEASUREMENTS
INTRODUCTION
• Measurement of any physical quantity involves comparison with a certain basic,
arbitrarily chosen, internationally accepted reference standard called unit .
• Fundamental or base quantities - Fundamental or base units .
Units obtained for the derived quantities - Derived units.
• International System of Units (SI) based on seven base units is at present
internationally accepted unit system .
1. Length (metre)
BASE UNITS - 2. Mass (Kg)
3. Time (sec)
4. Electric current (Ampere)
5. Thermodynamic temperature (kelvin)
6. Amount of substance (mole)
7. Luminous intensity (Candela)
• SIGNIFICANT FIGURE CONCEPT
• Reports Precision of the actual measurement
• Reliable Digit + First uncertain Digit
• Example - the length 2.308 cm has four significant figures.
But in different units, the same value can be written as 0.02308m or 23.08
mm or 23080 µm.
https://www.studifysuccess.com
Made by - Ahad
, These notes are provided by studifysuccess
Rules :
• 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.
• The terminal or trailing zero(s) in a
number without a decimal
point are not significant.
• The trailing zero(s) in a number with a
decimal point are significant.
• For a number greater than 1, without any
decimal, the trailing zero(s) are not
significant.
• For a number with a decimal, the trailing
zero(s) are significant.
FOR ARITHEMATIC OPERATION -
(1) 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.
(2) In addition or subtraction, the final result
should retain as many decimal places as are
there in the number with the least
decimal places.
https://www.studifysuccess.com Made by - Ahad
CLASS : 11 PHYSICS
Chapter 1
UNITS AND MEASUREMENTS
INTRODUCTION
• Measurement of any physical quantity involves comparison with a certain basic,
arbitrarily chosen, internationally accepted reference standard called unit .
• Fundamental or base quantities - Fundamental or base units .
Units obtained for the derived quantities - Derived units.
• International System of Units (SI) based on seven base units is at present
internationally accepted unit system .
1. Length (metre)
BASE UNITS - 2. Mass (Kg)
3. Time (sec)
4. Electric current (Ampere)
5. Thermodynamic temperature (kelvin)
6. Amount of substance (mole)
7. Luminous intensity (Candela)
• SIGNIFICANT FIGURE CONCEPT
• Reports Precision of the actual measurement
• Reliable Digit + First uncertain Digit
• Example - the length 2.308 cm has four significant figures.
But in different units, the same value can be written as 0.02308m or 23.08
mm or 23080 µm.
https://www.studifysuccess.com
Made by - Ahad
, These notes are provided by studifysuccess
Rules :
• 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.
• The terminal or trailing zero(s) in a
number without a decimal
point are not significant.
• The trailing zero(s) in a number with a
decimal point are significant.
• For a number greater than 1, without any
decimal, the trailing zero(s) are not
significant.
• For a number with a decimal, the trailing
zero(s) are significant.
FOR ARITHEMATIC OPERATION -
(1) 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.
(2) In addition or subtraction, the final result
should retain as many decimal places as are
there in the number with the least
decimal places.
https://www.studifysuccess.com Made by - Ahad
