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ComprehensiveObjective
PHYSICSFor Competitive Examinations
Volume—I
GOLDEN BELLS(AN IMPRINT OF LAXMI PUBLICATIONS PVT. LTD.)
� BANGALORE � CHENNAI � COCHIN � GUWAHATI � HYDERABAD
� JALANDHAR � KOLKATA � LUCKNOW � MUMBAI � RANCHI
NEW DELHI
ComprehensiveObjective
PHYSICSFor Competitive Examinations
Volume—I
By
NARINDER KUMARM.Sc. PES (I)
Department of PhysicsS.D. Govt. College
Ludhiana
&
Dr. J.K. JUNEJAM.Sc., M.Phil., Ph.D.
Department of PhysicsHindu College
Sonepat
RST
RST
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Revised Edition, 2006Reprint, 2007
C—128/06/06
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ComprehensiveObjective
PHYSICSVolume—I
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PREFACE TO THE SECOND EDITION
There is no dearth of competition books for engineering and medical entrance examinations. But there is no singlebook which completely satisfies the intelligent student. The present book is a serious attempt in this direction. We haveleft no stone unturned to get ‘EXTREMELY SATISFACTORY’ grade from the readers of the book.
Some salient features of the book are as under :(i) No superfluous question. Only those questions have been included which have either been already set in different
examinations or are expected to be set.(ii) Most systematic presentation. It is the only book in the market which has systematically categorised the study
material of each unit. The study material has been clearly demarcated in the following seven segments.1. SYNOPSIS2. SET I [Contains MCQs based on Memory Work, Hard Facts, Important Terms, Important Formulae etc.]3. SET II [Contains MCQs based on Important Basic Concepts, Application of Formulae and Brain Teasers]4. SET III [Contains MCQs with more than one correct alternative]5. SET IV [Contains MCQs based on Typical Numerical Bank]6. SELF-EVALUATION TEST I [Contains Expected Questions for Forthcoming Examinations]7. SELF-EVALUATION TEST IIIn addition to the above, ‘Knowledge Plus’ has also been included at some places.
(iii) Time-saving solutions. Special techniques have been used in solving questions. These techniques have been high-lighted at different places in the book. If the reader tries to grasp these techniques, considerable time will be saved.
The book has been divided into two volumes. The divisions are as under :
Units
Volume—I I—XTopics included
Mathematical Tools ; Introduction, Units, Measurements and Dimension ; Description of Motion in One Dimension ;Description of Motion in Two and Three Dimensions (Vectors ; Motion in Two and Three Dimensions) ; Laws ofMotion ; Work, Energy and Power ; Rotational Motion (Circular Motion ; Centre of Mass and Rotational Mechanics) ;Gravitation ; Properties of Matter (Elasticity ; Fluids at Rest ; Surface Tension ; Fluids in Motion ; Kinetic Theoryof Gases) ; Heat and Thermodynamics ; Oscillations and Waves.
Units
Volume—II XI—XVIIITopics included
Electrostatics ; Current Electricity ; Magnetic Effect of Current and Magnetism ; Electromagnetic Induction andAlternating Current ; Optics ; Dual Nature of Matter and Radiations ; Atomic Nucleus ; Solids and SemiconductorDevices, Electromagnetic Waves and Principles of Communication.3 Practice Papers are designed in such a way so as to enable the students to evaluate their skills in Volume—I andVolume—II separately.Model Test Papers based on full syllabus are included in Volume—II for Self Assessment.
Utmost effort has been made to make this book as best as possible. But it is our firm conviction that there is alwaysa scope for improvement. So, we invite your suggestions for the further improvement of the book. It would be ourearnest endeavour to incorporate all good suggestions in the next edition.
—AUTHORS
List of Chapters in Volume—I and Volume—II
Volume—I
Unit 0 MATHEMATICAL TOOLS
Unit I INTRODUCTION AND MEASUREMENT
1.01 Introduction, Units, Measurement and Dimension
1.02 Significant Figures and Error Analysis
Unit II DESCRIPTION OF MOTION IN ONE DIMENSION
Unit III DESCRIPTION OF MOTION IN TWO AND THREE DIMENSIONS
3.01 Vectors
3.02 Motion in Two and Three Dimensions
Unit IV LAWS OF MOTION
Unit V WORK, ENERGY AND POWER
Unit VI ROTATIONAL MOTION (Circular Motion, Centre of Mass and Rotational Mechanics)
Unit VII GRAVITATION
Unit VIII PROPERTIES OF MATTER
8.01 Elasticity
8.02 Fluids at Rest
8.03 Surface Tension
8.04 Fluids in Motion
8.05 Kinetic Theory of Gases
Unit IX HEAT AND THERMODYNAMICS
Unit X OSCILLATION AND WAVES
3 Practice Papers
Volume—II
Unit XI ELECTROSTATICS
Unit XII CURRENT ELECTRICITY
Unit XIII MAGNETIC EFFECT OF CURRENT AND MAGNETISM
Unit XIV ELECTROMAGNETIC INDUCTION AND ALTERNATING CURRENT
Unit XV OPTICS
Unit XVI DUAL NATURE OF MATTER AND RADIATIONS
Unit XVII ATOMIC NUCLEUS
Unit XVIII SOLIDS AND SEMICONDCUTOR DEVICES, ELECTROMAGNETIC WAVES ANDPRINCIPLES OF COMMUNICATION
3 Practice Papers
3 Model Test Papers based on Full Syllabus
Unit 0 MATHEMATICAL TOOLS 1
Unit I INTRODUCTION AND MEASUREMENT
CONTENTS
1.01. Introduction, Units, Measurements and Di-mension• Synopsis 15• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 28Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 41Concepts, Applications of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 58Alternative
Set IV : MCQs based on Typical Numerical 60Bank (Exclusively for EngineeringEntrance Test)
1.02. Significant Figures and Error Analysis• Synopsis 64
• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 70Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 74Concepts, Application of Formulae,Brain Teasers
Set III : MCQs based on Typical Numerical 79Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 80Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 85Solutions
Unit II DESCRIPTION OF MOTION IN ONE DIMENSION
2. Description of Motion in One Dimension• Synopsis 93• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 101Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 110Concepts, Application of Formulae,Brain Teasers
Set III : Graphical Bank (MCQs based on 130Graphs)
Set IV : MCQs with More than one Correct 144Alternative
Set V : MCQs based on Typical Numerical 148Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 153Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 160Solutions
Unit III DESCRIPTION OF MOTION IN TWO AND THREE DIMENSIONS
3.01. Vectors• Synopsis 171• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 177Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 188Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 202Alternative
Set IV : MCQs based on Typical Numerical 206Bank (Exclusively for EngineeringEntrance Tests)
3.02. Motion in Two and Three Dimensions• Synopsis 212• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 218Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 225Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 238Alternative
Set IV : MCQs based on Typical Numerical 240Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 246Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 252Solutions
Unit IV LAWS OF MOTION
4. Laws of Motion• Synopsis 261• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 271Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 279Concepts, Application of Formulae,Brain Teasers
Set III : MCQs With More than one Correct 314Alternative
Set IV : MCQs based on Typical Numerical 323Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 331Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 339Solutions
Unit V WORK, ENERGY AND POWER
5. Work, Energy and Power• Synopsis 351• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 358Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 367Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 393Alternative
Set IV : MCQs based on Typical Numerical 397Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 402Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 408Solutions
Unit VI ROTATIONAL MOTION
6. Circular Motion, Centre of Mass &Rotational Mechanics• Synopsis 419• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 435Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 450Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 483Alternative
Set IV : MCQs based on Typical Numerical 486Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 498Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 506Solutions
7. Gravitation• Synopsis 517• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 525Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 542Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 568Alternative
Set IV : MCQs based on Typical Numerical 570Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 574Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 582Solutions
Unit VII GRAVITATION
Unit VIII PROPERTIES OF MATTER
8.01. Elasticity• Synopsis 591• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 596Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 606Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 622Alternative
Set IV : MCQs based on Typical Numerical 625Bank (Exclusively for EngineeringEntrance Tests)
8.02. Fluids at Rest• Synopsis 631• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 633Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 639Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with more than one Correct 654Alternative
Set IV : MCQs based on Typical Numerical 657Bank (Exclusively for EngineeringEntrance Test)
8.03. Surface Tension• Synopsis 660• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 662Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 671Concepts. Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 679Alternative
Set IV : MCQs based on Typical Numerical 681Bank (Exclusively for EngineeringEntrance Tests)
8.04. Fluids in Motion• Synopsis 685• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 687Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 693Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 703Alternative
Set IV : MCQs based on Typical Numerical 705Bank (Exclusively for EngineeringEntrance Tests)
8.05. Kinetic Theory of Gases• Synopsis 709• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 711Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 721Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 731Alternative
Set IV : MCQs based on Typical Numerical 733Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 735Solutions (Expected Questions forForthcoming Examination)
• Self-Evaluation Test II with Answers/ 741Solutions
9. Heat and Thermodynamics• Synopsis 749• Question Bank with Answers/Questions
Set I : MCQs based on Memory Work, Hard 763Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 788Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 828Alternative
Set IV : MCQs based on Typical Numerical 831Bank (Exclusively for EngineeringEntrance Tests)
• Self-Evaluation Test I with Answers/ 837Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 842Solutions
Unit IX HEAT AND THERMODYNAMICS
Unit X OSCILLATIONS AND WAVES
10. Oscillations and Waves• Synopsis 851• Question Bank with Answers/Solutions
Set I : MCQs based on Memory Work, Hard 865Facts, Important Terms, ImportantFormulae etc.
Set II : MCQs based on Important Basic 880Concepts, Application of Formulae,Brain Teasers
Set III : MCQs with More than one Correct 919Alternative
Set IV : MCQs based on Typical Numerical 922Bank (Exclusively for EngineeringEntrance Test)
• Self-Evaluation Test I with Answers/ 925Solutions (Expected Questions forForthcoming Examinations)
• Self-Evaluation Test II with Answers/ 931Solutions
PRACTICE PAPERS BASED ON UNITS I—X
• Practice Paper 1 1• Practice Paper 2 7• Practice Paper 3 13
UNIT 0
*MATHEMATICAL TOOLS
Elementary concepts of differentiation and integration for describing motion.
1. GRAPHS
A diagrammatic representation of the variation ofone quantity with respect to another is called a graph. Agraph gives visual impression about how one quantity var-ies w.r.t. the other.
Suppose we want to depict the relation F = ma graphi-cally. If mass is regarded as constant, then F ∝ a. We knowthat the acceleration is determined by force. So, for the pur-pose of drawing a graph, force is the independent variableand acceleration is the dependent variable.
In any graph, the independent variable (thecause) is, by convention, represented along x-axis andthe dependent variable (the effect) is representedalong y-axis. Thus, in the problem under consideration,force will be plotted against x-axis and the acceleration willbe plotted against y-axis.
In order to plot a graph, we must have data, i.e., a setof values for the independent variable and of the correspondingvalues for the dependent variable. This data can be eitherexperimental or theoretical. The experimental data comprisesthe observed values of the quantities from an experiment.The theoretical data is obtained by feeding a particular valueof one quantity in a theoretical relationship and calculatingthe magnitude of the other quantity.
While drawing a graph, we have to choose a suitablescale. The scale chosen should be simple and convenient tooperate. It should not be so small that all the points of thedata get cramped together in a small portion of the graphpaper. The scale should also not be so large that the whole ofthe data cannot be represented on the graph paper.
2. USES OF GRAPHS
(i) From the shape of the graph, we can have a clearidea about the relationship between the two quantities
represented by it. If the graph is a straight line and passesthrough the origin, it is of the form y = mx. A straight linegraph having positive or negative intercepts on y-axis isrepresented by :
y = mx ± c(ii) The slope of the graph and its intercept on the x or
y-axis gives us the values of physical quantities.(iii) A graph helps in identifying the inaccuracies in
the experimental data.(iv) With the help of graph, we can determine the mean
value from a large number of observations.
3. TRIGONOMETRICAL FUNCTIONS
These are also known as trigonometric ratios orcircular functions of θ. The trigonometric function is so namedbecause to each value of θ, there corresponds one and onlyone value of a trigonometrical ratio of θ. It may be noted thateach trigonometrical ratio is a mere number.
Consider a revolving line which starts from OX andtraces out any ∠XOP = θ in the first quadrant.
From P, drop a perpendicular PM on X′OX. With dueregard to signs of OM, MP, OP, the trigonometrical ratios ofθ are defined as follows :
(i)MPOP
is called the sine of θ, written as sin θ ;
Y
XM
P
OX´
Y´
θ
Fig. 1
*Exclusively for those appearing in Medical Entrance Tests.
2 COMPREHENSIVE OBJECTIVE PHYSICS
(b) In the second quadrant, only the sine and (its re-ciprocal) cosecant are +ve.
(c) In the third quadrant, only the tangent and (itsreciprocal) cotangent are +ve.
(d) In the fourth quadrant, only the cosine and (itsreciprocal) secant are +ve.
Fig. 2 should serve as a good aid to memory.Let us now mention a few facts about the limits to the
values of T-ratios.(i) The maximum, i.e., greatest value of sin θ or cos
θ is 1. The minimum, i.e., least value of sin θ or cos θ is – 1.(ii) sec θ and cosec θ cannot be numerically less than
one.(iii) tan θ and cot θ can have any numerical values.
Aid to memory for values of T-ratios
0° 30° 45° 60° 90°
sine 02
12
22
32
42
*cosine 42
32
22
12
02
*sines written backwards.
5. T-RATIOS OF CERTAIN ALLIED ANGLES
An angle is said to be allied to an angle θ if their sumis 0°, or their sum or difference is a multiple of 90°.
I. sin (– θ) = – sin θ ; cos (– θ) = cos θ ;tan (– θ) = – tan θ ; cot (– θ) = – cot θ ;sec (– θ) = sec θ ; cosec (– θ) = – cosec θ
II. sin (90 – θ) = cos θ ; cos (90 – θ) = sin θ ;tan (90 – θ) = cot θ ; cot (90 – θ) = tan θ ;sec (90 – θ) = cosec θ ; cosec (90 – θ) = sec θ
III. sin (90 + θ) = cos θ ; cos (90 + θ) = – sin θ ;tan (90 + θ) = – cot θ ; cot (90 + θ) = – tan θ ;sec (90 + θ) = – cosec θ ; cosec (90 + θ) = sec θ
IV. sin (180 – θ) = sin θ ; cos (180 – θ) = – cos θ ;tan (180 – θ) = – tan θ ; cot (180 – θ) = – cot θ ;sec (180 – θ) = – sec θ ; cosec (180 – θ) = cosec θ
V. sin (180 + θ) = – sin θ ; cos (180 + θ) = – cos θ ;tan (180 + θ) = tan θ ; cot (180 + θ) = cot θ ;sec (180 + θ) = – sec θ ; cosec (180 + θ) = – cosec θ
VI. sin (270 – θ) = – cos θ ; cos (270 – θ) = – sin θ ;tan (270 – θ) = cot θ ; cot (270 – θ) = tan θ ;sec (270 – θ) = – cosec θ ; cosec (270 – θ) = – sec θ
VII. sin (270 + θ) = – cos θ ; cos (270 + θ) = sin θ ;tan (270 + θ) = – cot θ ; cot (270 + θ) = – tan θ ;sec (270 + θ) = cosec θ ; cosec (270 + θ) = – sec θ
(ii)OMOP
is called the cosine of θ, written as cos θ ;
(iii)MPOM
is called the tangent of θ, written as tan θ ;
(iv)OMMP
is called the cotangent of θ, written as cot θ ;
(v)OPOM
is called the secant of θ, written as sec θ ;
(vi)OPMP
is called the cosecant of θ, written as cosec θ.
Note. sin θ is not equal to sin × θ, i.e., sin is not a multiplier. Sinθ is a single symbol.
4. FUNDAMENTAL RELATIONS BETWEEN THET-RATIOS OF AN ANGLE
(i) cot θ = 1
tan θ(ii) sec θ =
1cos θ
(iii) cosec θ = 1
sin θ(iv) tan θ =
sincos
θθ
(v) cot θ = cossin
θθ
(vi) sin2 θ + cos2 θ = 1
(vii) sec2 θ = 1 + tan2 θ (viii) cosec2 θ = 1 + cot2 θ
Signs of T-ratios and Limits to the value of T-ratiosIn order to understand the signs of T-ratios, let us
first understand the rule for signs of the sides of the triangleOMP.
(i) OM is positive if it is drawn to the right of O andnegative if drawn to the left.
(ii) MP is positive if it is drawn above X′OX and nega-tive if drawn below X′OX.
(iii) OP is always positive.Keeping in mind this sign convention and the defini-
tions of T-ratios, we shall find that :(a) In the first quadrant, all the T-ratios are positive.
Y
XX´
Y´
O
SIN ALL
COSTAN
Fig. 2
MATHEMATICAL TOOLS 3
VIII. sin (360 – θ) = sin (– θ) = – sin θ ;cos (360 – θ) = cos (– θ) = cos θ ;tan (360 – θ) = tan (– θ) = – tan θ ;cot (360 – θ) = cot (– θ) = – cot θ ;sec (360 – θ) = sec (– θ) = sec θ ;cosec (360 – θ) = cosec (– θ) = – cosec θ
IX. sin (360 + θ) = sin θ ; cos (360 + θ) = cos θ ;tan (360 + θ) = tan θ ; cot (360 + θ) = cot θ ;sec (360 + θ) = sec θ ; cosec (360 + θ) = cosec θ.
Note 1. Each t-ratio of (n.360° + θ) is equal to the correspond-ing t-ratio of θ, n being any integer, +ve or –ve.
Note 2. Consider θ to be acute and find the quadrant in whichthe allied angle lies. The sign of the required t-ratio in this quadrant isthe required sign.
Note 3. If the allied angle is – θ or 180° ± θ, the t-ratio is notchanged in form. But if the allied angle is 90° ± θ or 270° ± θ, the t-ratiois changed in form.
Note 4. If the allied angle is 360° ± θ, subtract 360° from theangle and find the t-ratios of the resulting angle.
6. SOME IMPORTANT FORMULAE OF TRIGONO-METRY
(i) sin (A + B) = sin A cos B + cos A sin B(ii) cos (A + B) = cos A cos B – sin A sin B
(iii) tan (A + B) = tan A + tan B
1 tan A tan B−
(iv) sin (A – B) = sin A cos B – cos A sin B(v) cos (A – B) = cos A cos B + sin A sin B
(vi) tan (A – B) = tan A tan B
1 tan A tan B−
+
(vii) 2 sin A cos B = sin (A + B) + sin (A – B)(viii) 2 cos A sin B = sin (A + B) – sin (A – B)
(ix) 2 cos A cos B = cos (A + B) + cos (A – B)(x) 2 sin A sin B = cos (A – B) – cos (A + B)
(xi) sin C + sin D = 2 sin C + D
2C D
2cos
−
(xii) sin C – sin D = 2 cos C + D2
C D2
sin−
(xiii) cos C + cos D = 2 cos C + D2
C D2
cos−
(xiv) cos C – cos D = 2 sin C + D2
sinD C
2−
(xv) sin 2A = 2 sin A cos A(xvi) cos 2A = cos2 A – sin2 A
(xvii) cos 2A = 1 – 2 sin2 A (xviii) cos 2A = 2 cos2 A – 1
7. LOGARITHMS
Definition and notation of *LogarithmIf ax = N, then x is called the logarithm of N to the
base a. It is written as loga N. It is read as “log N to the basea.”
If ax = N, then loga N = x.So, logarithm of any number to a given base is the
power to which base must be raised to obtain that number.Illustration 1. ∵ 23 = 8∴ log2 8 = 3
Four formulae of LogarithmsI. loga mn = loga m + loga n (Product formula)
II. loga mn
= loga m – loga n (Quotient formula)
III. loga mn = n loga m (Power formula)IV. loga m = logb m × loga b (Base-changing formula)
8. TWO SYSTEMS OF LOGARITHMS
(i) Natural logarithms and (ii) Common logarithms.Logarithms to the base e are called natural loga-
rithms. These are used in theoretical calculations.e is the sum of the infinite series :
1 + 11
12
13! ! !
+ + + ......
Its value is 2.7182.Logarithms to the base 10 are called common loga-
rithms. These are used in arithmetical calculations.When the base of a logarithm is not mentioned, it is
understood to be 10. The word ‘logarithm’ generally meanscommon logarithm.
9. CHARACTERISTIC AND MANTISSA
The integral part of the logarithm of a number afterexpressing the decimal part as positive is called the charac-teristic. The positive decimal part is called the mantissa. Itis important to note that mantissa is always positive.
Illustration 2. The logarithm of a number is 2.3147.Find the characteristic and mantissa.
Sol. Since the decimal part of the logarithm is posi-tive,
∴ Characteristic = 2 and mantissa = .3147Illustration 3. The logarithm of a number is 0.2983.
Find the characteristic and mantissa.Sol. Since the decimal part of the logarithm is positive,∴ Characteristic = 0 and mantissa = .2983
*The literal meaning of the word ‘logarithm’ is to ‘cut downarithmetic’.
Comprehensive Objective Physics Vol.I For Competitive Examinations
Publisher : Laxmi Publications ISBN : 9788179680544Author : Prof. Narinderkumar, Dr. J. K. Juneja
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