Concepts of Physics by H.C. Verma for your NEET preparation:
Volume 1 , chapter 1
Units and Measurement
1.1. Fundamental Quantities and Units:
Physical Quantities: Physical quantities can be classified into two types:
Fundamental Quantities: These are independent and form the foundation of all other quantities. For
example:
Length (L): Measured in meters (m)
Mass (M): Measured in kilograms (kg)
Time (T): Measured in seconds (s)
These are the core quantities from which other measurements are derived.
Derived Quantities: These are derived from the fundamental quantities. For example:
Velocity (v) is derived from distance and time:
V=distance/time
Force (F) is derived from mass and acceleration:
F= ma
1.2. International System of Units (SI Units):
The SI system ensures standardization across measurements worldwide. SI Units are designed to
provide uniformity for scientific and engineering applications.
, Base Units (Fundamental Quantities):
Meter (m): Unit of length
Kilogram (kg): Unit of mass
Second (s): Unit of time
Ampere (A): Unit of electric current
Kelvin (K): Unit of thermodynamic temperature
Mole (mol): Unit of the amount of substance
Candela (cd): Unit of luminous intensity
These fundamental units allow scientists and engineers to communicate effectively across disciplines,
knowing that these quantities have the same standard definition worldwide.
1.3. Measurement of Physical Quantities:
Accuracy vs. Precision:
Accuracy measures how close a value is to the true or accepted value. If the measurement is
accurate, it is close to the real value.
Precision refers to the degree of reproducibility of measurements. If measurements are precise, they
are consistently the same, even if they’re not close to the true value.
Least Count: The least count is the smallest value that can be measured by an instrument. For
example:
A Vernier caliper might have a least count of 0.01 cm.
A micrometer screw gauge might have a least count of 0.001 cm.
This value is important because it limits the precision of the measurements taken.
Volume 1 , chapter 1
Units and Measurement
1.1. Fundamental Quantities and Units:
Physical Quantities: Physical quantities can be classified into two types:
Fundamental Quantities: These are independent and form the foundation of all other quantities. For
example:
Length (L): Measured in meters (m)
Mass (M): Measured in kilograms (kg)
Time (T): Measured in seconds (s)
These are the core quantities from which other measurements are derived.
Derived Quantities: These are derived from the fundamental quantities. For example:
Velocity (v) is derived from distance and time:
V=distance/time
Force (F) is derived from mass and acceleration:
F= ma
1.2. International System of Units (SI Units):
The SI system ensures standardization across measurements worldwide. SI Units are designed to
provide uniformity for scientific and engineering applications.
, Base Units (Fundamental Quantities):
Meter (m): Unit of length
Kilogram (kg): Unit of mass
Second (s): Unit of time
Ampere (A): Unit of electric current
Kelvin (K): Unit of thermodynamic temperature
Mole (mol): Unit of the amount of substance
Candela (cd): Unit of luminous intensity
These fundamental units allow scientists and engineers to communicate effectively across disciplines,
knowing that these quantities have the same standard definition worldwide.
1.3. Measurement of Physical Quantities:
Accuracy vs. Precision:
Accuracy measures how close a value is to the true or accepted value. If the measurement is
accurate, it is close to the real value.
Precision refers to the degree of reproducibility of measurements. If measurements are precise, they
are consistently the same, even if they’re not close to the true value.
Least Count: The least count is the smallest value that can be measured by an instrument. For
example:
A Vernier caliper might have a least count of 0.01 cm.
A micrometer screw gauge might have a least count of 0.001 cm.
This value is important because it limits the precision of the measurements taken.
