Units and Dimensions is a fundamental and essential topic in Physics. For the measurement of a physical quantity, Unit plays a vital role. Unit provides a complete idea about the measurement of a physical quantity. Dimension is a measure of the size or extent of a particular quantity.
Table of Contents
What are Units?
Units are values used to measure and express various physical quantities. Unit gives us a complete and clear idea about a physical quantity. Measurement of a physical quantity consists of mainly two parts – Numeric value and unit.
Measurement of physical quantity = Numerical value x Unit
For example, A rectangular garden has 50 meter length.
Here, “50” is the numeric value or magnitude, and “meter” is the Unit of the physical quantity.
Fundamental and Derived Units
Fundamental Units are independent to each other and these units are mainly used to measure the units of the fundamental physical quantities. There are seven fundamental units available namely – meter, kilogram, second, ampere, kelvin, candela and mole.
Derived Units are the units which are obtained from the fundamental units. Except fundamental units, all other units are known as Derived Units. The examples of Derived units are units of area, volume, momentum, speed, velocity, density, force, energy, work etc.
Fundamental Units
Fundamental units are also known as base units. There are total of 7 base units. Fundamental units and their Symbols in SI systemare discussed in the following table:
Physical Quantity
Name of Unit
Symbol
Length
meter
m
Mass
kilogram
kg
Time
second
s
Electric current
ampere
A
Thermodynamic temperature
kelvin
K
Amount of substance
mole
mol
Luminous intensity
candela
cd
System of Units
There are four system of units available namely – MKS System, CGS System, FPS System, and SI system.
MKS System: The full form ofMKS System is Metre Kilogram Second. In MKS system, the units of length, mass and time are respectively metre, kilogram and second.
CGS System : The full form of CGS system is Centimetre Gram Second. CGS system is also known as Gaussian system. In CGS system, the units of length, mass and time are respectively centimetre, gram and second.
FPS System : The full form of FPS System is Foot Pound Second. FPS is also known as British system. In FPS system, the units of length, mass and time are respectively foot, pound and second.
SI System : SI system is generally known as International System of Units. It is the modification form of MKS system. SI System of unit is adopted to have same common unit world-wide.
Macro and Micro Prefixes
Micro- is a prefix used to describe something that is small scale, while macro- is a prefix used to describe something that is large scale.
Macro Prefix
Symbol
Value
kilo
k
103
mega
M
106
giga
G
109
tera
T
1012
peta
P
1015
exa
E
1018
zetta
Z
1021
yotta
Y
1024
Micro Prefix
Symbol
Value
centi
c
10-2
milli
m
10-3
micro
μ
10-6
nano
n
10-9
pico
p
10-12
femto
f
10-15
atto
a
10-18
zepto
z
10-21
yocto
y
10-24
Units of Length, Mass and Time
The different units used to represent length, mass and time are shown below in the table:
Units of Length
Units of Mass
Units of Time
1 Angstrom = 10-10 m
1 Quintal = 102 kg
1 minute = 60 second
1 Light year = 9.46 × 1015 m
1 Metric tone = 103 kg
1 Hour = 60 minute = 3600 second
1 AU ( Astronomical Unit) = 1.5 × 1011 m
1 Atomic mass unit = 1.66 × 10-27 kg
1 Day = 24 hours = 1440 min = 86400 s
1 Mile = 1.6 km
1 Pound = 0.4537 kg
1 Lunar month = 28 days
1 Fermi = 10-15 m
1 Slug = 14.59 kg
1 Solar month = 30 or 31 days
Important Formulas of Derived Units
Following table shows some of the examples of derived units from fundamental units.
What are Dimensions?
Dimensions of a physical quantity are defined as the powers to which the fundamental quantities should be raised to represent that physical quantity. Dimension of a physical quantity is not dependent on the magnitude or the numeric value of that physical quantity.
To represent dimensions of physical quantities, we use square bracket “[ ]” around the quantity.
Dimensional Formula
Dimensional formula is nothing but an expression that shows how the fundamental units and which of the fundamental units are required to represent the unit of physical quantity.
The process of writing of a dimensional formula of a physical quantity is by enclosing the symbols of the base quantities with appropriate power in square brackets.
Dimensions of fundamental physical quantities along with their dimensional symbols are written as –
Pressure, Stress, modulus of elasticity, energy density.
Force constant, surface tension, surface energy.
Frequency, Angular velocity, velocity gradient.
Gravitational potential, latent heat.
Entropy, Thermal capacity, universal gas constant and Boltzmann’s constant.
Force, thrust.
Power, luminous flux.
Dimensionless Quantities
Dimensionless quantities are the physical quantities which have no dimension or zero dimension. Its numeric value or magnitude is same in all system of units.
Examples : The examples of dimensionless quantities are as follows:
Angle
Solid angle
Relative density
Specific gravity
Uses of Dimension
Dimension of a physical quantity is an essential part. It has following uses –
It is used to convert the units from one measurement system to another measurement system.
It helps to establish relationship among various physical quantities.
It is used to ensure an equation is homogeneous or not.
FAQs on Units and Dimensions
What are the 7 dimension units?
The seven dimension base units are as follows –
Length – meter (m)
Time – second (s)
Amount of substance – mole (mole)
Electric current – ampere (A)
Temperature – kelvin (K)
Luminous intensity – candela (cd)
Mass – kilogram (kg)
What is the SI unit of speed?
The SI unit of speed is m/s or m s-1.
What is the SI unit of temperature?
The SI unit of temperature is kelvin.
What is the SI unit for energy?
The SI unit of energy is joule.
What are Dimensional Variables?
The physical quantities which have dimensions but do not have fixed numerical value, is called the Dimensional Variables. Examples : velocity, acceleration, force, work, power, etc are the examples of Dimensional variables.
What is Dimensional Analysis?
Dimensional analysis can be defined as the process of checking relations among various physical quantities by using the dimensions of the physical quantities. These are independent of the numerical values and constants.
What are Dimensional Constants?
The physical quantities those have dimensions and have fixed values, are called dimensional constants. For Example:
Gravitational constant (G)
Planck’s constant (h)
Velocity of light in a vacuum (C)
Universal gas constant (R)
What is Law of Homogeneity of Dimensions?
Principle of Homogeneity states that dimensions of each of the terms of a dimensional equation on both sides should be the same.
Neeraj Anand, Param Anand
Er. Neeraj K.Anand is a freelance mentor and writer who specializes in Engineering & Science subjects. Neeraj Anand received a B.Tech degree in Electronics and Communication Engineering from N.I.T Warangal & M.Tech Post Graduation from IETE, New Delhi. He has over 30 years of teaching experience and serves as the Head of Department of ANAND CLASSES. He concentrated all his energy and experiences in academics and subsequently grew up as one of the best mentors in the country for students aspiring for success in competitive examinations.
In parallel, he started a Technical Publication "ANAND TECHNICAL PUBLISHERS" in 2002 and Educational Newspaper "NATIONAL EDUCATION NEWS" in 2014 at Jalandhar. Now he is a Director of leading publication "ANAND TECHNICAL PUBLISHERS", "ANAND CLASSES" and "NATIONAL EDUCATION NEWS".
He has published more than hundred books in the field of Physics, Mathematics, Computers and Information Technology. Besides this he has written many books to help students prepare for IIT-JEE and AIPMT entrance exams. He is an executive member of the IEEE (Institute of Electrical & Electronics Engineers. USA) and honorary member of many Indian scientific societies such as Institution of Electronics & Telecommunication Engineers, Aeronautical Society of India, Bioinformatics Institute of India, Institution of Engineers. He has got award from American Biographical Institute Board of International Research in the year 2005.
Below we have provided the details of the CBSE Physics topics under each unit as per the revised CBSE Class 11 Physics Syllabus for the 2023-24 academic year. Go through it to get the details of the chapters given below.
Unit-I: Physical World and Measurement
Chapter 2: Units and Measurements
Need for measurement: Units of measurement; systems of units; SI units, fundamental and derived units. Length, mass and time measurements; accuracy and precision of measuring instruments; errors in measurement; significant figures.
Dimensions of physical quantities, dimensional analysis and its applications.
Unit-II: Kinematics
Chapter 3: Motion in a Straight Line
Frame of reference, Motion in a straight line, Elementary concepts of differentiation and integration for describing motion, uniform and nonuniform motion, and instantaneous velocity, uniformly accelerated motion, velocity-time and position-time graphs. Relations for uniformly accelerated motion (graphical treatment).
Chapter 4: Motion in a Plane
Scalar and vector quantities; position and displacement vectors, general vectors and their notations; equality of vectors, multiplication of vectors by a real number; addition and subtraction of vectors, relative velocity, Unit vector; resolution of a vector in a plane, rectangular components, Scalar and Vector product of vectors.
Motion in a plane, cases of uniform velocity and uniform acceleration-projectile motion, uniform circular motion.
Unit-III: Laws of Motion
Chapter 5: Laws of Motion
Intuitive concept of force, Inertia, Newton’s first law of motion; momentum and Newton’s second law of motion; impulse; Newton’s third law of motion (recapitulation only). Law of conservation of linear momentum and its applications. Equilibrium of concurrent forces, Static and kinetic friction, laws of friction, rolling friction, lubrication.
Dynamics of uniform circular motion: Centripetal force, examples of circular motion (vehicle on a level circular road, vehicle on a banked road).
Unit-IV: Work, Energy and Power
Chapter 6: Work, Energy and Power
Work done by a constant force and a variable force; kinetic energy, work-energy theorem, power.
Notion of potential energy, potential energy of a spring, conservative forces: conservation of mechanical energy (kinetic and potential energies); non-conservative forces: motion in a vertical circle; elastic and inelastic collisions in one and two dimensions.
Unit-V: Motion of System of Particles and Rigid Body
Chapter 7: System of Particles and Rotational Motion
Centre of mass of a two-particle system, momentum conservation and centre of mass motion. Centre of mass of a rigid body; centre of mass of a uniform rod. Moment of a force, torque, angular momentum, law of conservation of angular momentum and its applications.
Equilibrium of rigid bodies, rigid body rotation and equations of rotational motion, comparison of linear and rotational motions.
Moment of inertia, radius of gyration, values of moments of inertia for simple geometrical objects (no derivation).
Unit-VI: Gravitation
Chapter 8: Gravitation
Kepler’s laws of planetary motion, universal law of gravitation. Acceleration due to gravity and its variation with altitude and depth. Gravitational potential energy and gravitational potential, escape speed, orbital velocity of a satellite.
Unit-VII: Properties of Bulk Matter
Chapter 9: Mechanical Properties of Solids
Elasticity, Stress-strain relationship, Hooke’s law, Young’s modulus, bulk modulus, shear modulus of rigidity (qualitative idea only), Poisson’s ratio; elastic energy.
Chapter 10: Mechanical Properties of Fluids
Pressure due to a fluid column; Pascal’s law and its applications (hydraulic lift and hydraulic brakes), effect of gravity on fluid pressure.
Viscosity, Stokes’ law, terminal velocity, streamline and turbulent flow, critical velocity, Bernoulli’s theorem and its applications.
Surface energy and surface tension, angle of contact, excess of pressure across a curved surface, application of surface tension ideas to drops, bubbles and capillary rise.
Chapter 11: Thermal Properties of Matter
Heat, temperature,( recapitulation only) thermal expansion; thermal expansion of solids, liquids and gases, anomalous expansion of water; specific heat capacity; Cp, Cv – calorimetry; change of state – latent heat capacity.
Heat transfer-conduction, convection and radiation (recapitulation only), thermal conductivity, qualitative ideas of Blackbody radiation, Wein’s displacement Law, Stefan’s law.
Unit-VIII: Thermodynamics
Chapter 12: Thermodynamics
Thermal equilibrium and definition of temperature (zeroth law of thermodynamics), heat, work and internal energy. First law of thermodynamics, Second law of thermodynamics: gaseous state of matter, change of condition of gaseous state -isothermal, adiabatic, reversible, irreversible, and cyclic processes.
Unit-IX: Behaviour of Perfect Gases and Kinetic Theory of Gases
Chapter 13: Kinetic Theory
Equation of state of a perfect gas, work done in compressing a gas.
Kinetic theory of gases – assumptions, concept of pressure. Kinetic interpretation of temperature; rms speed of gas molecules; degrees of freedom, law of equi-partition of energy (statement only) and application to specific heat capacities of gases; concept of mean free path, Avogadro’s number.
Unit-X: Oscillations and Waves
Chapter 14: Oscillations
Periodic motion – time period, frequency, displacement as a function of time, periodic functions and their application.
Simple harmonic motion (S.H.M) and its equations of motion; phase; oscillations of a loaded spring- restoring force and force constant; energy in S.H.M. Kinetic and potential energies; simple pendulum derivation of expression for its time period.
Chapter 15: Waves
Wave motion: Transverse and longitudinal waves, speed of travelling wave, displacement relation for a progressive wave, principle of superposition of waves, reflection of waves, standing waves in strings and organ pipes, fundamental mode and harmonics, Beats.
Students can also access the syllabus for other subjects by visiting Syllabus page of CBSE Class 11.
CBSE Syllabus for Class 11 Physics Practical
Below are the list of the experiments of Physics practicals.
Evaluation Scheme for Class 11 Physics Practical 2023-24
Topic
Marks
Two experiments, one from each section
7 + 7
Practical record (experiment and activities)
5
One activity from any section
3
Investigatory Project
3
Viva on experiments, activities and project
5
Total
30
CBSE Class 11 Physics Practical Syllabus
Section – A
CBSE 11 Physics Syllabus Experiments
1. To measure the diameter of a small spherical/cylindrical body and to measure internal diameter and depth of a given beaker/calorimeter using Vernier Callipers and hence find its volume. 2. To measure the diameter of a given wire and thickness of a given sheet using screw gauge. 3. To determine the volume of an irregular lamina using the screw gauge. 4. To determine the radius of curvature of a given spherical surface by a spherometer. 5. To determine the mass of two different objects using a beam balance. 6. To find the weight of a given body using parallelogram law of vectors. 7. Using a simple pendulum, plot its L-T2 graph and use it to find the effective length of second’s pendulum. 8. To study variation of time period of a simple pendulum of a given length by taking bobs of same size but different masses and interpret the result. 9. To study the relationship between force of limiting friction and normal reaction and to find the co- efficient of friction between a block and a horizontal surface. 10. To find the downward force, along an inclined plane, acting on a roller due to gravitational pull of the earth and study its relationship with the angle of inclination θ by plotting graph between force and sin θ.
CBSE 11 Physics Syllabus Activities
1. To make a paper scale of given least count, e.g., 0.2cm, 0.5 cm. 2. To determine mass of a given body using a metre scale by principle of moments. 3. To plot a graph for a given set of data, with proper choice of scales and error bars. 4. To measure the force of limiting friction for rolling of a roller on a horizontal plane. 5. To study the variation in range of a projectile with angle of projection. 6. To study the conservation of energy of a ball rolling down on an inclined plane (using a double inclined plane). 7. To study dissipation of energy of a simple pendulum by plotting a graph between square of amplitude and time.
Section – B
CBSE 11 Physics Syllabus Experiments
1. To determine Young’s modulus of elasticity of the material of a given wire. 2. To find the force constant of a helical spring by plotting a graph between load and extension. 3. To study the variation in volume with pressure for a sample of air at constant temperature by plotting graphs between P and V, and between P and 1/V. 4. To determine the surface tension of water by capillary rise method. 5. To determine the coefficient of viscosity of a given viscous liquid by measuring terminal velocity of a given spherical body. 6. To study the relationship between the temperature of a hot body and time by plotting a cooling curve. 7. To determine specific heat capacity of a given solid by method of mixtures. 8. To study the relation between frequency and length of a given wire under constant tension using sonometer. 9. To study the relation between the length of a given wire and tension for constant frequency using sonometer. 10. To find the speed of sound in air at room temperature using a resonance tube by two resonance positions.
CBSE 11 Physics Syllabus Activities
1. To observe change of state and plot a cooling curve for molten wax. 2. To observe and explain the effect of heating on a bi-metallic strip. 3. To note the change in level of liquid in a container on heating and interpret the observations. 4. To study the effect of detergent on surface tension of water by observing capillary rise. 5. To study the factors affecting the rate of loss of heat of a liquid. 6. To study the effect of load on depression of a suitably clamped metre scale loaded at (i) its end (ii) in the middle. 7. To observe the decrease in pressure with increase in velocity of a fluid.
Practical Examination for Visually Impaired Students of Class 11 Evaluation Scheme
Time: 2 Hours Max. Marks: 30
Topic
Marks
Identification/Familiarity with the apparatus
5
Written test (based on given/prescribed practicals)
10
Practical Record
5
Viva
10
Total
30
A. Items for Identification/Familiarity of the apparatus for assessment in practicals (All experiments).
Spherical ball, Cylindrical objects, vernier calipers, beaker, calorimeter, Screw gauge, wire, Beam balance, spring balance, weight box, gram and milligram weights, forcep, Parallelogram law of vectors apparatus, pulleys and pans used in the same ‘weights’ used, Bob and string used in a simple pendulum, meter scale, split cork, suspension arrangement, stop clock/stop watch, Helical spring, suspension arrangement used, weights, arrangement used for measuring extension, Sonometer, Wedges, pan and pulley used in it, ‘weights’ Tuning Fork, Meter scale, Beam balance, Weight box, gram and milligram weights, forceps, Resonance Tube, Tuning Fork, Meter scale, Flask/Beaker used for adding water.
B. List of Practicals
1. To measure diameter of a small spherical/cylindrical body using vernier calipers. 2. To measure the internal diameter and depth of a given beaker/calorimeter using vernier calipers and hence find its volume. 3. To measure diameter of given wire using screw gauge. 4. To measure thickness of a given sheet using screw gauge. 5. To determine the mass of a given object using a beam balance. 6. To find the weight of given body using the parallelogram law of vectors. 7. Using a simple pendulum plot L-T and L-T2 graphs. Hence find the effective length of second’s pendulum using appropriate length values. 8. To find the force constant of given helical spring by plotting a graph between load and extension. 9. (i) To study the relation between frequency and length of a given wire under constant tension using a sonometer. (ii) To study the relation between the length of a given wire and tension, for constant frequency, using a sonometer. 10. To find the speed of sound in air, at room temperature, using a resonance tube, by observing the two resonance positions.
Note: The above practicals of CBSE 11 Physics Syllabus may be carried out in an experiential manner rather than recording observations.
Did you find CBSE 11 Physics Syllabus useful for your studies? Do let us know your view in the comment section. Get access to interactive lessons and videos related to CBSE Maths and Science with ANAND CLASSES (A School Of Competitions) – The Learning App.
Frequently Asked Questions on CBSE Class 11 Physics Syllabus
Q1
According to the CBSE Class 11 Physics Syllabus, which are the units of high marks weightage?
According to the CBSE Class 11 Physics Syllabus, physical world and measurement, kinematics and laws of motion are the units of high-mark weightage.
Q2
How is the practical syllabus of the CBSE Class 11 Physics divided into sections A and B?
The practical syllabus of the CBSE Class 11 Physics contains 10 experiments in section A and 10 experiments in section B with 7 physical activities mentioned for each.
Q3
Which are the basic concepts present in the CBSE Syllabus for Class 11 Physics?
The basic concepts present in the CBSE Syllabus for Class 11 Physics are Thermodynamics, Laws of Motion, Oscillations and Waves.
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