CHAPTER
1 Unit and Measurement
Sr.
Concept Formulas Other information
No.
1. Classification Physical Quantities
Independent of any Dependent on other
other quantity quantities
Fundamental Derived
2. Fundamental Physical quantity Unit Symbol Example of derived
quantities and
Length metre m quantities:
their SI units
(1) Area
Mass kilogram kg
(2) Force
Time second s (3) Density
Temperature kelvin K
Electric current ampere A
Luminous intensity candela cd
Amount of substance mole mol
n = numerical value of
1
3. For magnitude n nu = constant the physical quantity
of physical u
u = size of unit.
quantity Or, n1u1 = n2u2
numerical
value and unit
relation
ds
4. Supplementary Plane angle - Radian (rad)- d = r = radius
quantities and r
dA ds = arc length
their SI units Solid angle - Steradian (sr) - d = 2
r dA = subtended area
NEET (XI) PHYSICS 1
,Sr.
Concept Formulas Other information
No.
5. Dimensional [M] → for mass
representation [L] → for length
[T] → for time
[A] → for electric current
[K] or [] → for thermodynamic temperature
[cd] → for luminous intensity
[mol] → for amount of substance
6. Principle of Only physical quantities having same dimension can be For example:
Homogeneity added or subtracted. A+B=C–D
The physical quantities
A, B, C, and D have the
same dimension.
7. To convert a If dimension of a physical quantity is represented by n1 = numerical value in
physical [ M a LbT c ] then: 1st system.
quantity from n2 = numerical value in
a b c
one system of M L T
n2 = n1 1 1 1 2nd system
units to other M 2 L2 T2
8. Rules to find Rule I: All the non-zero digits are significant e.g. 1984 has 4 In multiplication or
out the number SF. division, the number of
of significant Rule II: All the zeros between two non-zero digits are SF in the product or
figures (SF) significant e.g. 10806 has 5 SF. quotient is same as the
Rule III: All the zeros to the left of first non-zero digit are smallest number of SF
not significant, e.g. 00108 has 3 SF. in any of the factors.
Rule IV: If the number is less than 1, zeros on the right of e.g. 2.4 × 3.65 = 8.8
the decimal point but to the left of the first non zero digit are
not significant, e.g. 0.002308 has 4 SF.
Rule V: The trailing zeros (zeros to the right of the last non-
zero digit) in a number with a decimal point are significant,
e.g. 01.080 has 4 SF.
Rule VI: The trailing zeros in a number without a decimal
point may not be significant e g. 010100 has 3 SF.
Rule VII: For any value written in notation A 10 x , the
number of S.F. is determined by applying the above rules
only to the value of A.
For example, in
x = 12.3 = 1.23 101 = 0.123 102 = 0.0123 103 = 123 10 −1
each term has 3 SF only.
NEET (XI) PHYSICS 2
,Sr.
Concept Formulas Other information
No.
9. Rounding off Rule I: If the digit to be rounded off is more than 5, then the
preceding digit is increased by one.
e.g. 6.87 6.9
Rule II: If the digit to be rounded off is less than 5, then the
preceding digit is left unchanged.
e.g. 3.94 3.9
Rule III: If the digit to be rounded off is 5 then the
preceding digit is increased by one if it is odd and is left
unchanged if it is even.
e.g. 14.35 14.4 and 14.45 14.4
10. Significant The answer equals the smallest number of decimal places in
3.1421
rules for any of the original numbers. 0.241
addition and + 0.09 (has two
subtraction 3.4731 decimal
places)
(Answer should be
reported to two
decimal places after
rounding off)
Answer = 3.47
11. Significant The answer equals the smallest number of significant figures
51.028
rules for in any of the original numbers.
1.31 (Three
multiplication 66.84668 significant
and division figures)
(Answer should have
three significant figures
after rounding off)
Answer = 66.8
12. Least Count Least Count = 1 MSD – 1 VSD If n VSD coincides with
n −1 1 MSD (n–1) MSD,
(Vernier Least Count = 1 MSD − MSD =
n n Then (n–1) MSD = n VSD
Caliper)
n −1
1 VSD = MSD
n
13. Total reading Total Reading = Main scale reading + (Conciding Verneir MSR = Main scale
(Vernier Scale division least count) reading
Caliper) Total reading = MSR + VSR VC = Vernier constant
= MSR + n VC i.e. least count
n = nth division of the vernier scale coinciding with the main
scale.
NEET (XI) PHYSICS 3
, Sr.
Concept Formulas Other information
No.
14. Screw Gauge Pitch of the screw gauge
Distance moved in n - rotation of circular - scale
=
No. of full - rotation
Pitch
L.C =
Total number of division on the circular scale
15. Total reading Total Reading (T.R) = L.S.R. + C.S.R
(Screw Gauge) L.S.R = Linear Scale Reading = N n = division of the
circular scale coinciding
C.S. R = Circular Scale Reading = n L.C
with the linear scale line
Total reading = N + n (L.C)
16. Zero Error in Negative Zero Error Correct reading =
Screw Gauge (Reading) – (zero error)
Positive Zero Error
17. Zero Error in 1. If the zero of the Vernier
scale is to the right of the
Vernier
zero of the main scale, the
Caliper
zero error is said to be
positive.
2. If the zero of the Vernier
scale is to the left of the zero
of the main scale, the zero
error is said to be negative.
NEET (XI) PHYSICS 4
1 Unit and Measurement
Sr.
Concept Formulas Other information
No.
1. Classification Physical Quantities
Independent of any Dependent on other
other quantity quantities
Fundamental Derived
2. Fundamental Physical quantity Unit Symbol Example of derived
quantities and
Length metre m quantities:
their SI units
(1) Area
Mass kilogram kg
(2) Force
Time second s (3) Density
Temperature kelvin K
Electric current ampere A
Luminous intensity candela cd
Amount of substance mole mol
n = numerical value of
1
3. For magnitude n nu = constant the physical quantity
of physical u
u = size of unit.
quantity Or, n1u1 = n2u2
numerical
value and unit
relation
ds
4. Supplementary Plane angle - Radian (rad)- d = r = radius
quantities and r
dA ds = arc length
their SI units Solid angle - Steradian (sr) - d = 2
r dA = subtended area
NEET (XI) PHYSICS 1
,Sr.
Concept Formulas Other information
No.
5. Dimensional [M] → for mass
representation [L] → for length
[T] → for time
[A] → for electric current
[K] or [] → for thermodynamic temperature
[cd] → for luminous intensity
[mol] → for amount of substance
6. Principle of Only physical quantities having same dimension can be For example:
Homogeneity added or subtracted. A+B=C–D
The physical quantities
A, B, C, and D have the
same dimension.
7. To convert a If dimension of a physical quantity is represented by n1 = numerical value in
physical [ M a LbT c ] then: 1st system.
quantity from n2 = numerical value in
a b c
one system of M L T
n2 = n1 1 1 1 2nd system
units to other M 2 L2 T2
8. Rules to find Rule I: All the non-zero digits are significant e.g. 1984 has 4 In multiplication or
out the number SF. division, the number of
of significant Rule II: All the zeros between two non-zero digits are SF in the product or
figures (SF) significant e.g. 10806 has 5 SF. quotient is same as the
Rule III: All the zeros to the left of first non-zero digit are smallest number of SF
not significant, e.g. 00108 has 3 SF. in any of the factors.
Rule IV: If the number is less than 1, zeros on the right of e.g. 2.4 × 3.65 = 8.8
the decimal point but to the left of the first non zero digit are
not significant, e.g. 0.002308 has 4 SF.
Rule V: The trailing zeros (zeros to the right of the last non-
zero digit) in a number with a decimal point are significant,
e.g. 01.080 has 4 SF.
Rule VI: The trailing zeros in a number without a decimal
point may not be significant e g. 010100 has 3 SF.
Rule VII: For any value written in notation A 10 x , the
number of S.F. is determined by applying the above rules
only to the value of A.
For example, in
x = 12.3 = 1.23 101 = 0.123 102 = 0.0123 103 = 123 10 −1
each term has 3 SF only.
NEET (XI) PHYSICS 2
,Sr.
Concept Formulas Other information
No.
9. Rounding off Rule I: If the digit to be rounded off is more than 5, then the
preceding digit is increased by one.
e.g. 6.87 6.9
Rule II: If the digit to be rounded off is less than 5, then the
preceding digit is left unchanged.
e.g. 3.94 3.9
Rule III: If the digit to be rounded off is 5 then the
preceding digit is increased by one if it is odd and is left
unchanged if it is even.
e.g. 14.35 14.4 and 14.45 14.4
10. Significant The answer equals the smallest number of decimal places in
3.1421
rules for any of the original numbers. 0.241
addition and + 0.09 (has two
subtraction 3.4731 decimal
places)
(Answer should be
reported to two
decimal places after
rounding off)
Answer = 3.47
11. Significant The answer equals the smallest number of significant figures
51.028
rules for in any of the original numbers.
1.31 (Three
multiplication 66.84668 significant
and division figures)
(Answer should have
three significant figures
after rounding off)
Answer = 66.8
12. Least Count Least Count = 1 MSD – 1 VSD If n VSD coincides with
n −1 1 MSD (n–1) MSD,
(Vernier Least Count = 1 MSD − MSD =
n n Then (n–1) MSD = n VSD
Caliper)
n −1
1 VSD = MSD
n
13. Total reading Total Reading = Main scale reading + (Conciding Verneir MSR = Main scale
(Vernier Scale division least count) reading
Caliper) Total reading = MSR + VSR VC = Vernier constant
= MSR + n VC i.e. least count
n = nth division of the vernier scale coinciding with the main
scale.
NEET (XI) PHYSICS 3
, Sr.
Concept Formulas Other information
No.
14. Screw Gauge Pitch of the screw gauge
Distance moved in n - rotation of circular - scale
=
No. of full - rotation
Pitch
L.C =
Total number of division on the circular scale
15. Total reading Total Reading (T.R) = L.S.R. + C.S.R
(Screw Gauge) L.S.R = Linear Scale Reading = N n = division of the
circular scale coinciding
C.S. R = Circular Scale Reading = n L.C
with the linear scale line
Total reading = N + n (L.C)
16. Zero Error in Negative Zero Error Correct reading =
Screw Gauge (Reading) – (zero error)
Positive Zero Error
17. Zero Error in 1. If the zero of the Vernier
scale is to the right of the
Vernier
zero of the main scale, the
Caliper
zero error is said to be
positive.
2. If the zero of the Vernier
scale is to the left of the zero
of the main scale, the zero
error is said to be negative.
NEET (XI) PHYSICS 4
