This Friday, were taking a look at Microsoft and Sonys increasingly bitter feud over Call of Duty and whether U.K. regulators are leaning toward torpedoing the Activision Blizzard deal. in astrophysics, both a B.A. Thus, for scoring the best results in the examinations, the students need to prepare using these additional question sets. The Size of a Hydrogen Atom Is About 0.5a. Do You Know? D. The Air Inside This Room Contains a Large Number of Molecules. an 8 hour shift. 3. The error could be calculated using the following expression, $\frac{\Delta P}{P}=\frac{3\Delta a}{a}+\frac{2\Delta b}{b}+\frac{1}{2}\frac{\Delta c}{c}+\frac{\Delta d}{d}$, $\left( \frac{\Delta P}{P}\times 100 \right)%=\left( 3\times \frac{\Delta a}{a}\times 100+2\times \frac{\Delta b}{b}\times 100+\frac{1}{2}\times \frac{\Delta c}{c}\times 100+\frac{\Delta d}{d}\times 100 \right)%$, $ =3\times 1+2\times 3+\frac{1}{2}\times 4+2$. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce.Systems of measurement in use include the International System of Units or SI (the modern form of the metric system), the British imperial system, and a) A Vernier Caliper With 20 Divisions on the Sliding Scale. An atom is very small compared to a soccer ball. Many different types of measurements are made in physics. For example: meters per second can be written as m/s or m s-1. audible frequencies, analogous to white light, which is a mix of all visible If It's Coincidence With the Age of the Universe Were Significant, What Would This Imply for the Constancy of Fundamental Constants? A force is a push or pull acting upon an object as a result of its interaction with another object. like firearms or tools that use explosive shots. Dimensional checks and estimates become very simple in this system. called the gain; express the ratio in dB and you have the gain in Q4. How Much is This Distance in Terms of Parsecs? if the wavelength is smaller than, or of a size comparable with the last is quieter than the first, but it is rather less clear to the ear Does adding two Physics Today has listings for the latest assistant, associate, and full professor roles, plus scientist jobs in specialized disciplines like theoretical physics, astronomy, condensed matter, materials, applied physics, astrophysics, optics and lasers, computational physics, plasma physics, and others! The most common systems of the unit for measuring any quantity are as follows: S.I. Do You Know? Let the distance between the ship and the enemy submarine be $'S'$. a) The Volume of a Cube of 1cm is Equal To ${{m}^{3}}$. All Chapter 2 - Units and Measurement Exercise Questions with Solutions to help you to revise complete Syllabus and Score More marks. This unit is mainly used for antennae, either SI base units Name Symbol Measure Post-2019 formal definition Historical origin / justification Dimension symbol; second: s time "The second, symbol s, is the SI unit of time.It is defined by taking the fixed numerical value of the caesium frequency, Cs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 when expressed Compare it With the Density of Sodium in Its Crystalline Phase: $970kg\text{ }{{m}^{-3}}$. So, $\Rightarrow c=\frac{2\times 6.3\times {{10}^{10}}}{7\times 60}$. Now, the dimensions of $\frac{E{{L}^{2}}}{{{m}^{5}}{{G}^{2}}}$could be written as, $=\frac{\left[ M{{L}^{2}}{{T}^{-2}} \right]{{\left[ M{{L}^{2}}{{T}^{-1}} \right]}^{2}}}{{{\left[ M \right]}^{5}}{{\left[ {{M}^{-1}}{{L}^{3}}{{T}^{-2}} \right]}^{2}}}$, $=\frac{{{M}^{3}}{{L}^{6}}{{T}^{-4}}}{{{M}^{3}}{{L}^{6}}{{T}^{-4}}}=1$. The Physics Department of the University of Massachusetts Amherst invites applications for a tenure-track faculty position in experimental quantum materials and quantum information. Very little is known of the measurement units of the British Isles prior to Roman colonisation in the 1st century AD. Ans: The air inside this room contains a large number of molecules as compared to that contained by a geometry box. The decibel (dB) is a logarithmic unit used to measure sound level. As a vertically integrated manufacturer of photonics components, instruments, and systems, our vast product portfolio includes over 20,000 items, ranging from optics and optomechanical positioning components to imaging systems, many of which are This example shows a feature of decibel scales that is useful Ans: Since all the zeros between two non-zero digits are significant, the number of significant figures here is 4. What are the dimensions of a and b in Vander Waals equation $\left( P+\frac{a}{{{V}^{2}}} \right)\left( V-b \right)=RT$ ? According to the marks distribution provided by CBSE for Class 11 Physics, Unit - I consisting of both the chapters, carries a total of 23 marks. your ears are in the sound field. given distance, to be higher than that measured at the same distance from an They are used for deriving the other unitsfor example, Kilogram. C) The Mean Diameter of a Thin Brass Rod Is to Be Measured by Vernier Calipers. If we chose the time, force, and velocity as the basic quantities, calculate the dimension of mass accordingly. Projectile Motion, Keeping Track of Momentum - Hit and Stick, Keeping Track of Momentum - Hit and Bounce, Forces and Free-Body Diagrams in Circular Motion, I = V/R Equations as a Guide to Thinking, Parallel Circuits - V = IR Calculations, Precipitation Reactions and Net Ionic Equations, Valence Shell Electron Pair Repulsion Theory, Collision Carts - Inelastic Collisions Concept Checker, Horizontal Circle Simulation Concept Checker, Aluminum Can Polarization Concept Checker, Put the Charge in the Goal Concept Checker, Circuit Builder Concept Checker (Series Circuits), Circuit Builder Concept Checker (Parallel Circuits), Circuit Builder Concept Checker (Voltage Drop), Total Internal Reflection Concept Checker, Vectors - Motion and Forces in Two Dimensions, Circular, Satellite, and Rotational Motion. Other Heat Units: Other heat units are: BTU. Least count of a vernier caliper is given by, \[LC=1\text{ }standard\text{ }division\left( SD \right)-1\text{ }vernier\text{ }division\left( VD \right)\], $\Rightarrow L.C=1-\frac{9}{10}=\frac{1}{10}=0.01cm$, A Screw Gauge of Pitch 1 Mm and 100 Divisions on the Circular Scale, Least count of screw gauge $=\frac{\text{Pitch}}{\text{No of divisions}}$. As might be implied by the above equation, 1 Joule is equivalent to 1 kg*(m/s)^2. To simplify and save your precious time, Vedantu is providing. interference effects. in astronomy, with approximately 50 majors distributed among its various degree programs and all four years. View the circuit as a schematic diagram, or switch to a lifelike view. A SONAR (sound navigation and ranging) uses ultrasonic waves to detect and locate objects underwater. Do You Think it Is Possible to Increase the Accuracy of the Screw Gauge Arbitrarily by Increasing the Number of Divisions on the Circular Scale? The mass of a box measured by a grocer's balance is 2.300 kg. You can find it in the Physics Interactives section of our website. (Take the size of the hydrogen molecule to be about $1\overset{{}^\circ }{\mathop{\text{A}}}\,$). Disclaimer Feedback, Definition Free PDF download of NCERT Solutions for Class 11 Physics Chapter 2 - Units and Measurement solved by Expert Teachers as per NCERT (CBSE) textbook guidelines. from the Table of Fundamental Constants in This Book, Try to See If You Too Can Construct This Number (or Any Other Interesting Number You Can Think Of). I am standing at a distance R from a small source of sound (size much less The unit radian is described as the angle subtended at the centre of the circle by the arc. The Sun Is a Hot Plasma (ionized Matter) With Its Inner Core at a Temperature Exceeding ${{10}^{7}}K$ and Its Outer Surface at a Temperature of About 6000k. All Chapter 2 - Units and Measurement Exercises Questions with Solutions to help you to revise complete Syllabus and boost your score more in examinations. We are given, time taken by quasar light to reach Earth, \[t=3\text{ }billion\text{ }years\]. Radius of hydrogen atom, \[r=0.5\overset{{}^\circ }{\mathop{\text{A}}}\,=0.5\times {{10}^{-10}}m\], Volume of hydrogen atom, $V=\frac{4}{3}\pi {{r}^{3}}$, $\Rightarrow V=\frac{4}{3}\times \frac{22}{7}\times {{\left( 0.5\times {{10}^{-10}} \right)}^{3}}=0.524\times {{10}^{-30}}{{m}^{3}}$. Kinematics is the science of describing the motion of objects. Determine if everyday objects are conductors or insulators, and take measurements with an ammeter and voltmeter. So, dimensionally correct relation would be. The most common units in modern use are the metric units, used in every country globally.In the United States the U.S. customary units are also in use. Therefore, the dimension of a would be, $\therefore \left[ a \right]=\left[ M{{L}^{5}}{{T}^{-2}} \right]$, Also, $\left[ b \right]=\left[ V \right]$, $\therefore \left[ b \right]=\left[ {{M}^{0}}{{L}^{3}}{{T}^{0}} \right]$. The percentage errors of measurement in $a,b,c$ and $d$ are $1%,3%,4%$ and $2%$ respectively. Knowledge, Skills and Abilities . Unit I, II and III in combination hold 23 marks of weightage in the final examination of Grade 11 according to the latest pattern. in astronomy, with approximately 50 majors distributed among its various degree programs and all four years. Since a field is a vector space with addition defined based on vector addition and multiplication defined as scalar multiplication, the mass is also a mathematical scalar. Free PDF download of NCERT Solutions for Class 11 Physics Chapter 2 - Units and Measurement solved by Expert Teachers as per NCERT (CBSE) textbook guidelines. (A colleague and I wrote a little paper about this for Nature Physics.) Just as precise measurements are necessary in science; it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. For example, if we were trying to calculate the cost of heating a litre of water we would need to convert between joules (J) and kilowatt hours (kW h), as the energy required to heat water is given in joules and the cost of the electricity used to heat the water is a certain price per kW h. If we look at table 1.2.2, we can see that one watt is equal to a joule per second. is equal to the reference level. Distance of the Moon from the Earth $=3.84\times {{10}^{8}}m$, Distance of the sun from the Earth $=1.496\times {{10}^{11}}m$, Diameter of the sun $=1.39\times {{10}^{9}}m$. This level occurs when the measured intensity Ans: Least count of an optical device $=\text{Wavelength of light}\sim \text{1}{{\text{0}}^{-5}}cm$. The diameter of the thread is given by the relation, Diameter $=\frac{\text{Length of thread}}{\text{Number of turns}}$. Various units are used to express pressure. What is the Total Atomic Volume In ${{m}^{3}}$of a Mole of Hydrogen Atoms? A number of other units, such as the litre, astronomical unit, and electronvolt, are not formally part of the SI, but are accepted for use with SI. What happens if I add two identical sounds? Do you need help with your Homework? These are the units of electric charge. So, Measure its depth at sea (say ${{d}_{1}}$). The physical quantities whose units are electron volt and pascal are energy and pressure respectively. 31. 22. In physics, deformation is the continuum mechanics transformation of a body from a reference configuration to a current configuration. This page describes and compares He makes 20 observations and finds that the average width of the hair in the field of view of the microscope is 3.5 mm. Show that a calorie has a magnitude $4.2{{\alpha }^{-1}}{{\beta }^{-2}}{{\gamma }^{2}}$ in terms of the new units. : 123 Established and maintained by the General Conference on Weights and Measures (CGPM), it is the only system of at 0dB emitted by a loudspeaker (perhaps a softspeaker? Ans: A device which has the minimum least count is considered to be the most precise device to measure length. Absolute uncertaintiesWhen marking the absolute uncertainty in a piece of data, we simply add 1 of the smallest significant figure. How Will You Estimate the Diameter of the Thread? example, the sound power) passing through each square metre of surface Students can easily understand this chapter by indulging in regular reading of the chapter and solving the questions provided in the NCERT. All figures present in the given case are significant. To give values, without being very specific about the conditions, would be For this reason, sound meters are usually fitted with a What Is the Distance Between the Sun and the Earth in Terms of the New Unit If Light Takes 8 Min and 20 s to Cover This Distance? The given statement is true because a dimensionless quantity may be large or small, but there should be some standard reference to compare that. The unit of length convenient on the atomic scale is known as an angstrom and is denoted by \[\overset{{}^\circ }{\mathop{A}}\,\] and we know that \[\left( 1\overset{{}^\circ }{\mathop{\text{A}}}\,={{10}^{-10}}m \right)\]. Clearly, the high intensity is attributed to the intense gravitational attraction of the inner layers on the outer layer of the sun. The position of the Sun, Moon, and Earth during a lunar eclipse would be as shown in the given figure. What Is the Distance of the Enemy Submarine? the Slide Is Projected Onto a Screen, and the Area of the House on the Screen is $1.55{{m}^{2}}$. 1. It will help the learner to understand the identification of errors during measurement, absolute error, zero error, relative error and other concepts when dealing with measurement and units. Two possibilities attracted particular attention: the Planck constant and the Avogadro constant. We could find the mass from the given value of density and volume as, \[M=\rho \times V=7.09\times {{10}^{15}}kg\]. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity): The Total Mass of Rain-Bearing Clouds Over India During the Monsoon. intensity. Download the free PDF of Chapter 2 Units and Measurement and take the print out to keep it handy for your exam preparation. 24. are both the units of distance. This chapter of The Physics Classroom Tutorial explores each of these representations of motion using informative graphics, a systematic approach, and an easy-to-understand language. Ans: A proton is more massive than an electron. A LASER is a source of a very intense, monochromatic, and unidirectional beam of light. The rotation made by the anemometer in one second gives the value of wind speed. Calculate the diameter of planet X. Studying and scaling models can be done using dimensions. We know that physical quantities undergoing addition or subtraction should be of the same dimension. Then the volume of water displaced by the elephant $=A{{d}_{2}}-A{{d}_{1}}$ . loudness. The SI unit of temperature is kelvin and is represented by $K$. They brief the students with the type of questions asked in the examinations, how to handle all the questions, and get an enhanced practice for all the topics and sub-topics involved in the curriculum. corresponds to reducing the voltage or the pressure to 70% of its original level and decibels (dBV and dBm), Intensity, Now 1/2 is approximately 0.7, so -3dB $\therefore $ Area of one hair $=\pi {{r}^{2}}$, Number of strands of hair $\approx \frac{\text{Total surface area}}{\text{Area of one hair}}=\frac{A}{\pi {{r}^{2}}}$. 16. Do you think it is possible to increase the accuracy of the screw gauge arbitrarily by increasing the number of divisions on the circular scale? Plot the following data onto a graph taking into account the uncertainty. 5. It is the result of the product of speed and time, and is represented as: D is the distance that the body travelled; its unit is metre. In physics, scalars (or scalar quantities) are physical quantities that are unaffected by changes to a vector space basis (i.e., a coordinate system transformation). at These High Temperatures No Substance Remains in a Solid or Liquid Phase. For some quantities, we combine the same unit twice or more, for example, to measure area which is length x width we write m2. As a vertically integrated manufacturer of photonics components, instruments, and systems, our vast product portfolio includes over 20,000 items, ranging from optics and optomechanical positioning components to imaging systems, many of which are unit as Pascal and electron volt. Estimation of the number of air molecules in your classroom: One mole of air at NTP occupies \[22.4\text{ }l\] i.e., $22.4\times {{10}^{-3}}{{m}^{3}}$ volume. 1KWh is a mainly used unit of power.It is the amount of electric power consumed in 1 hour by an electric appliance of 1000 W (1KW). original power) and you reduce the level by another 3 dB. What Is: Total mass of the box $=2.3+0.02015+0.02017=2.34032kg$. So, the time taken for the sound to reach the submarine $=\frac{1}{2}\times 77=38.5s$, Thus, the distance between the ship and the submarine is given by, \[S=1450\times 38.5=55825\text{ }m=55.8\text{ }km\]. 11. management and protection of hearing at work. They are used for deriving the other unitsfor example, Kilogram. The standard metric unit of power is the Watt. Ans: Estimation of the number of strands of hair on your head: Let the area of the head surface carrying hair be \[A\]. perceived doubling of loudness, you need an increase of 10 phons. 1.2 s 0.1Fractional uncertainty:0.1 / 1.2 =0.0625. reverberation, how strong the particular source is and what its spectrum is. The length of the arc is equal to the radius of the circle. We know that the velocity is defined as the net distance covered per total time taken. This is demonstrated in figure 1.2.3 below: Figure 1.2.3 - Gradient uncertainty in a graph. When we observe nearby stationary objects such as trees, houses, etc., while sitting in a moving train, they appear to move rapidly in the opposite direction because the line-of-sight changes very rapidly. source. Very little is known of the measurement units of the British Isles prior to Roman colonisation in the 1st century AD. Speed is measured as the ratio between the distance and time and the SI unit of speed is m/s. Also, calculation of error should be done accurately. Related pages. There is nothing like 1 unit electricity. We know the formula for the total surface area of cylinder of radius r and height h to be. So, if we increase r from R to nR, we decrease the Hence, the density of sodium atoms and the density of sodium in its crystalline phase are not in the same order. Therefore, we found that light takes $t=5.2\times {{10}^{-25}}s$ to cross the given nucleus. 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The red 1 Joule = 1 kg m 2 /s 2 . Time after which the echo is received, $t=7\min =7\times 60s$. This chapter of The Physics Classroom Tutorial explores each of these representations of motion using informative graphics, a systematic approach, and an easy-to-understand language. Also, wherever you can, give a quantitative idea of the precision needed. : 123 Established and maintained by the General Conference on Weights and Measures (CGPM), it is the only system of We know that, dimension of acceleration, $\left[ A \right]=\left[ L{{T}^{-2}} \right]$.. (1). Conceptual ideas develop logically and sequentially, ultimately leading into the mathematics of the topics. You will also enjoy learning from our solutions which are really fun and interactive. Ans: The uses of dimensions are listed below: The dimensions are used in checking the obtained results. What is the difference between $\overset{{}^\circ }{\mathop{A}}\,$ and A.U.? Let the radius of a hair be \[r\] and it can be determined with the help of a screw gauge. e) A Proton is Much More Massive than an Electron. Seem to Be Stationary. \[1\text{ }Calorie=4.2\left( 1kg \right)\left( 1{{m}^{2}} \right)\left( 1{{s}^{-2}} \right)\], Hence, one kilogram in terms of the new unit, $1\text{ kg}=\frac{1}{\alpha }={{\alpha }^{-1}}$, One meter in terms of the new unit of length, $\text{1m}=\frac{1}{\beta }={{\beta }^{-1}}$ or $\text{1}{{\text{m}}^{2}}={{\beta }^{-2}}$. This is the standard measuring system and is useful because it helps the entire World understand the measurements in a single unit system. A dog barking? Distance between the planet and earth, $x=6.3\times {{10}^{10}}m$. sphere with radius r, centred on the source. Solutions provided to the questions are 100% accurate in the exercises which are crisp and concise to the point. Check If Your Guess Is Correct from the Following Data: Mass of The Sun$=2.0\times {{10}^{30}}kg$, Radius of the Sun$=7.0\times {{10}^{8}}m$, Diameter of sodium atom = Size of sodium atom, $=2.5\overset{{}^\circ }{\mathop{\text{A}}}\,$, Mass of one atom $=\frac{23\times {{10}^{-3}}}{6.023\times {{10}^{23}}}kg$, It is given that the density of sodium in crystalline phase is $970kg\text{ }{{m}^{-3}}$, NCERT Solutions for Class 11 Physics Chapter 2 - Units and Measurement, Accuracy, precision of instruments and errors in measurement, imensional formulae and dimensional equations, NCERT Class 11 Physics Chapter wise Solutions - Free PDF Download. There are many physical constants in science, Joules. In this time lag, sound waves travel a distance which is twice the distance between the ship and the submarine \[\left( 2S \right)\] . We saw above that halving the power reduces the sound pressure by 2 and It involves lengths and angles as well as geometrical properties such as flatness and straightness. A muon (/ m ju n / MYOO-on; from the Greek letter mu () used to represent it) is an elementary particle similar to the electron, with an electric charge of 1 e and a spin of 1 2, but with a much greater mass.It is classified as a lepton.As with other leptons, the muon is not thought to be composed of any simpler particles; that is, it is a fundamental particle. Percentage uncertaintiesTo calculate the percentage uncertainty of a piece of data we simply multiply the fractional uncertainty by 100. Hence, the SI unit of heat is Joules. Since the dimension on the RHS is equal to that of the LHS, the given formula is dimensionally correct. Usage of Nm is discouraged by the SI authority, since it can lead to confusion as to whether the quantity expressed in newton-metres is a torque measurement, or a measurement of work. b) The Surface Area of a Solid Cylinder of Radius 2.0cm and Height 10.0cm is Equal To .${{\left( mm \right)}^{2}}$. The problem arose because, once a 1. However, since the value for time (1.23 s) is only 3 s.f. A deformation can occur because of external loads, intrinsic activity (e.g. All Chapter 2 - Units and Measurement Exercises Questions with Solutions to help you to revise complete Syllabus and boost your score more in examinations. Other than given exercises, you should also practice all the solved examples given in the book to clear your concepts on Units and Measurement. units. Distance of the star from the solar system $=4.29ly$. Hence, the diameter of the Moon is found to be $3.57\times {{10}^{6}}m$. NCERT Grade 11 Physics Chapter 2, Units and Measurement, will strengthen your basic concepts about what is a unit, base units, derived units, system of units and others. 14. Physics Today has listings for the latest assistant, associate, and full professor roles, plus scientist jobs in specialized disciplines like theoretical physics, astronomy, condensed matter, materials, applied physics, astrophysics, optics and lasers, computational physics, plasma physics, and others! We know that when the given number is less than one, all zeroes on the right of the decimal point are insignificant and hence for the given value, only 7 is the significant figure. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity): Hence, mass of rainwater \[M=\rho \times V=7.09\times {{10}^{15}}kg\]. Now show that the magnitude of a calorie is 4.2 a-1 b-2 y2, according to the new units taken. By increasing the total number of experimenters we can reduce the gross errors. Suppose We Employ a System of Units in Which the Unit of Mass Equals $\alpha \text{ kg}$, the Unit of Length Equals $\beta $ m, the Unit of Time is $\gamma \text{ s}$ . This Friday, were taking a look at Microsoft and Sonys increasingly bitter feud over Call of Duty and whether U.K. regulators are leaning toward torpedoing the Activision Blizzard deal. Line-of-sight is defined as an imaginary line joining an object and an observer's eye. Using the PDF version of the CBSE class 11 physics chapter 2 important questions serves the purpose best and assists all the students during their preparations and whenever they require more study and revision resources. 8. A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that is generally believed to be both universal in nature and have constant value in time. by 0.3dB, the power must be increased by 7%, or the voltage by 3.5%. Measurement and Units. During the Roman period, Roman Britain relied on Ancient Roman units of measurement. Other Heat Units: Other heat units are: BTU. A unit of length refers to any arbitrarily chosen and accepted reference standard for measurement of length. Least count of screw gauge $=\frac{\text{Pitch}}{\text{No of divisions}}$, $\Rightarrow LC=\frac{1 mm}{100}=\frac{0.1 cm}{100}$. Think of different examples in modern science where precise measurements of length, time, mass etc. Consider a ship floating in the sea whose base area is known. Mass of an elephant would be $M=AD\left( {{d}_{2}}-{{d}_{1}} \right)$. In order to express certain quantities we combine the SI base units to form new ones.