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# 11th Class Chapter one Physics Short Questions

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##### Question: 1
What is importance of bivalent formation?.
1-102
Due to bivalent formation of homologous chromosomes,the non sister chromatids exchange their segment during the crossing over resulting in new recombination.
##### Question: 2
What is physical significance of dimension of physical quantity?
2-102
Each base quantity is considered a dimension. It stands for the qualitative nature of the physical quantity. Dimensions give information about the nature of a physical quantity, its units of measure and correctness of physical equation.
##### Question: 3
Define acromegaly. Give its cause.
3-102
Abnormal increase in size of appendages and other body parts sue to excess release of thyroxin is called acromegaly.
##### Question: 4
Why a screw gauge measures more accurately than a vernier cllipers
4-102
Because least count of screw guage is 0.01mm and divide 1mm into 10 equal parts. But least count of vernier calipers is 0.1mm and 1mm. divide into 10 equal parts.
##### Question: 5
Does dimensional analysis give any information on constant of proportionality that may appear in algebraic expression? Explain.
5-102
Dimensional analysis does not give any information about constant of proportionality in any expression.This constant can be determined by experiments.
##### Question: 6
What events occur in anaphase-I in meiosis?
6-102
During the anaphase of meiosis -1.The spindle fibers contract and each member of homologous chromosomes moves toward each pole.In this way half chromosomes reaches to one pole and other half reaches to another pole.
##### Question: 7
Write down two rules to find the significant digits in measurement
7-102
Rules to find significant digits are following
Zero between significant figures are always significant.
##### Question: 8
Discuss the various branches of physics?
8-102
The various branches of physics are given below.
1. Mechanies:It is the branch of physics which deals with the study of motion of material objects under the action of forces
2. Heat:It is the branch of physics which deals with the study of nature, properties and uses of heat energy.
3. Light:It is the branch of physics which deals with the study of nature, properties and use of light energy
4. Electricity and Magnetism: It is the branch of physics which deals with the properties of charge at the rest as well as in motion.
5. Atomic Physics:It is the branch of physics which deals with the structures and properties of individual atoms.
6. Nuclear Physics:It is the branch of physics which deals with the properties of nucleus.
7. Solid State Physics:The branch of physics which deals with the physical properties of solids is known as solid state physics.
8. Elementary particle physics:It is the branch of physics which deals with deals with the study of sub-atomic particles.
9. Plasma Physics:It is the branch of physics which deals with the study of properties of ionized gases
10. Astrophysics:It is the branch of physics which deals with the study of biology based on the principle of physics.
11. Geo - physics:It is the branch of physics which deals with the study of earth and its atmosphere.
12. Health Physics:It is the branch of physics which deals with the study of diseases and their treatment.
##### Question: 9
Define Physics.
9-102
The branch of science which deals with study of matter and energy and the relationships between them is called physics.
##### Question: 10
Explain " Rounding off numbers ?
10-102
The quantities in a measurement are always rounded off to certain level of accuracy. The following rules must be observed while rounding off a number.
1. If the dropping digits is less than "5" then the last retained digit is kept as it is For example 863.73 is rounded to 863.7
2. If the dropping digits is greater than '5' then the last retained digits is increased by '1' for example 9.66 is rounded to 9.7
3. If the dropping digits is '5' and the last retained digit is even then it will be remain uneffected. For example 66.45 is rounded to 66.4
4. If the dropping is '5' and the last retained digit is add, then it will be increases by '1' for example 76.35 is rounded to 76.4
##### Question: 11
Define least count and write meter rod's least count
11-102
smallest measurement hat can be taken by an instrument is called least count of that instrument Least Count
##### Question: 12
Add the mass given in kg up to appropriate precision: 2.189,0.089,11.8 and 5.32.
12-102
As m= 2.189+0.089 +11.8+5.32+19.398 kg
By appropriate precision m= 19.4kg
##### Question: 13
Explain dimension of physics quantities ?
13-102
The power to which the fundamental units of first system must be raised to give the unit of a physics quantities are called dimensions of that quantity
Explanation:The dimension represents the nature of a physics quantity. It tells us that how a quantities is related to the base units .It is represented by capital letters in a square brackets For example
1. Dimension of mass length time are respectively written as [M] , [L]
Use of dimensions.
1. The dimension are used for checking the correctness of an equation or formula
2. The dimension are used for deriving of certain formula for a physics quantity.
##### Question: 14
Differentiate between the precision and accuracy.
14-102
Precision: A measurement which has less absolute uncertainty is called precise measurement. The precision of a measurement is determined by the instrument being used.Absolute uncertainty , in effect, is equal to the least count of measuring instrument.
Accuracy: is the one which has less fractional or percentage error. Accuracy measures,how close a measured value is to the actual value.
##### Question: 15
Discuss the conventions for using SI units?
15-102
The various conventions for using SI are given below.
1. Full name of the unit does not begin with a capital letter even if named after a scientist.
2. symbol of unit name after scientist has initial capital latter for for example N for newton Pa for pascal H3 for hertz etc
3. The prefixes is written before an adjacent to the unit
4. The combination of units is written each with one space a part For example , Torque =55 N m
5. Double, triple etc prefixes are not allowed
6. When a multiple of base unit is raised to a power. The power applies to the whole multiple and not just the base unit
7. Before substituting values in the formula to calculate the final result make sure that all the included physical quantities are expressed in their SI units.
##### Question: 16
Differentiate between law of conservation of Energy.
16-102
Energy can neither be created place by created nor, destroyed , but can be changed from one form to another is called Law of Conservation of Energy.
If a chemical change takes place by several different routes, the overall energy change is the same , regardless of the route by which the chemical change occurs, provided the initial and final conditions are the same is known as Hess's Law.
##### Question: 17
Write down the two uses of dimensional analysis.
17-102
It is used for .
• Checking the homogeneity of the physical equation.
• Deriving the possible formula.
##### Question: 18
Define the term "Joule" and convert 15 calories to joules?
18-102
The energy expanded when a force of one Newton move an object one meter in the direction in which force is applied. Where one joule is equal 107 Ergs and 1 cal =4.184 J and 15 cal = 4.184x15=62.76J
##### Question: 19
Define physical quantities and derived quantities.
19-102
Physical quantites: All measurable quantities are called physical quantities.
##### Question: 20
Define error and uncertainty ? Discuss the various types of error ?
20-102
Error:The difference between measured value and actual value is known as error.
Uncertainty:The errors which a rises due to natural imperfection of the experimenter the limitation of the apparatus and the change in the environment during the measurement is known as Uncertainty
Types of Errors:There are three type of errors which are given below.
1. Personal Error:The error due to carelessness or improper knowledge about an instrument or incorrect reading of a scale by an experimenter is known as personal error. The personal error can be removed to some extent error if the experimenter take care during the measurement of any quantity and have proper knowledge about the measuring instrument.
2. Systematic Error:The error due to faulty apparatus and poor calibration of the instrument is known as systematic error. The systematic error also a rises from zero error between scales as in vernier caliper screw gauge and spherometer. The systematic error can be removed by comparing the faulty instrument with some accurate and standard instrument. the difference of the two can be added tracted to the measurement if the error is positive then will be subtracted from faulty instrument reading for correctness. If the error is negative, then it will be added to the foulty instruments reading for correctness
3. Statistical Error:The error due to repeated measurements of same quantity under same condition that result in different values of the same quantity is known random error.
##### Question: 21
Described the principle of homogeneity of dimensional analysis.
21-102
According to homogeneity principle
"If the dimensions of physical quantities on both sides of equation are the same, then the equation will be dimensionally correct".
##### Question: 22
Define the term light.
22-102
Light is the form of energy. Light is electromagnetic radiation that can be detected by the human eye. Light is a general term that is commonly used to refer to the visible spectrum.Visible menas something that can be seen using the eye, as opposed to invisible" things that cannot be seen
##### Question: 23
Sate the Hess's law of constant heat summation?
23-102
It states "If a chemical reaction takes place by different ways, the net change in energy is same regardless of the route by which the chemical change occurs.
##### Question: 24
Differentiate between precise and accurate measurement.
24-102
Precis Measurement: A measurement which has less absolute uncertainty is called precise measurement.

Accurate Measurement: is the one which has less fractional or percentage error.
##### Question: 25
Define nuclear physics.
25-102
The branch of physics which deals with the study of the constituent particles and interactions of atomic nuclei is called Nuclear Physics.
##### Question: 26
What is physics ? Discuss the importance of physics ?
26-102
Physics:
The branch of science which deals with the properties of matter energy and their mutual relationship is known as physics.
Physics has played on importance role in our daily life.
1. The electronic media like T.V, radio, Loudspeaker, Telephone, cell phone, Photo phone for machine etc are the important source of communication which works on the principles of physics.
2. Information technology is based on the principle of physics which is the scientific method of storing, protecting, processing, Transmitting, receiving and retrieving information
3. The whole world has become a global village due to use of computer net works which works on the principles of physics.
4. Atomic bomb is the invention of physics which can be used for the production of huge amount of energy. It can be also used for defence purposes.
5. X-rays, Y-rays Laser rays etc. are the inventions of physics which can be used in industry, health and agriculture department for various purposes.
6. Cathode ray oscilloscope (C.R.O) is the invention of physics which can be used as graph plotting device to see the wave from of a repetitive electronic signals the C.R.O can be also used in T.V circuits in computers system and as A.C circuits or D.C circuits circuits.
7. All means of transport, like aeroplane buses, motor cycles, railways etc work on the principles of physics
8. Electricity is the invention of physics without which we can not imagine any machine in working conditions
9. Rockets and satellites are the invention of physics with the help of which we can get information about the upper atmosphere.
10. The simple machine like pulley, wedge, like leaver screw-jack etc are the invention of physics which can be used for various purposes invention of physics which can be used for various purpose in daily life.
11. Physics explain the natural phenomena in term of fundamental principles and basics and basic Laws
12. Electron microscope is the invention of physics which is used to see distant objects clearly.
13. Microphone is the invention of physics which can be used to study microorganisms clearly and easily
14. Telescope is the invention of physics which is used to see distance objects clearly.
15. Physics employs the essential steps of scientific method observation recording analysis prediction and verification.
##### Question: 27
Is a zero significant or not? Explain.

27-102
Azero may or may not be significant. The following rules are used.
• A zero between two significant figures is itself significant.
• Zeros to the left of significant figures are not significant .
• In decimal fraction, zeros to the right of a significant figure are significant.
However , in integers, the number of significant zeros is determined by the accuracy of the measuring instrument.
• In scientific notation, the digits other than the powers of ten are significant.
##### Question: 28
What dose the word "micro" signify in the words "micro wave oven ?
28-102
Micro means very small. Micro waves have the shortest wavelength of all the shortest wavelengths of all the radio waves, therefore, these are known as microwaves. Now like all electromagnetic waves the microwaves produces heating effect when their energy is absorbed. It is because, due to shorter wave length the micro waves posses high frequency and maximum energy.
##### Question: 29
Express the following quantities using prefixes.
29-102
5000 g
##### Question: 30
What are three fundamental frontiers of fundamental science?
30-102
The three fundamental frontiers of fundamental science are:
1. The world of extremely large bodies.
2. The world of extremely small objects.
3. The world of middle sized objects. OR The world of complex matter.
##### Question: 31
Explain the term " precision" and accuracy ?
31-102
The 'Precision represents the magnitude of error in a measurement while the accuracy means to check how the measured values are closer to the actual value. The accuracy represents the relative error. It can be obtained by dividing the error with measured quantity.
The accuracy depends on the error if the error is greater than smaller will be the accuracy of the measurements and vice versa.
The accuracy of the measurements can be increased by taking several readings and take their average.
##### Question: 32
What is the usual way to obtain plan wavefront from a point source?
32-102
A usual way to obtain a plane wavefront is to place a point source of light at the focus of a convex lens. The rays coming out of the lens will constitute plane waves.
##### Question: 33
Define Base and Derived Units.
33-102
Base Unit: The unit that describe base quantities are called base units.
Examples: Unit of length is meter and Unit of mass is kilogram.
##### Question: 34
What rules are of rounded off the significant figure?
34-102
1. If the first digit dropped is less than 5, the last digit retained should remain unchanged.
2. If the first digit dropped is more than 5, the digit to be retained is increased by one.
3. If the first digit to be dropped is 5 the previous digit which is to be retained is increased by one if it is odd and retained as such if it is even.
##### Question: 35
Define Born-Haber cycle and lattice energy?
35-102
Born-Haber Cycle: The sum of energy changes for a closed cyclic process is zero, If the initial and final states are same.
Lattice Energy: The amount of energy released when gaseous ions of opposite charges combine to give one mole of a crystalline ionic compound.
##### Question: 36
An old saying is that " A chain is only as strong as its weakest link , " What analogous statement can you make regarding measurement ?
36-102
The analogous statement is that the result of an experimental data which is as accurate as measurements can be used in the computation.
##### Question: 37
What do you mean by prefixes of the power of ten? Explain?
37-102
These are the certain specific power of ten which have been given special name and symbols and are frequently used in measurement.Explanation:Sometimes, we have to deal with quantities that are very large or very small as compared to the base unit. under such condition, we higher or lower unit of the base unit.For convenience, we express a large or small number by using certain prefixes, such as eenti, milli, Micro, Kilo, etc to the number they are given special names and symbols and certain power of 10 to multiply a quantity
##### Question: 38
Write two uses of X-rays diffraction by crystals.
38-102
X-ray diffraction has been very useful in determining the structure of biologically important molecules such as hemoglobin and double helix structure of DNA.
##### Question: 39
Define derived units.
39-102
The units associated with the derived quantities are called derived units. SI units for measuring all other physical quantities are derived from the base and supplementary units. For Example, newton, joule, watt, pascal etc.
##### Question: 40
Enthalpy is a state function Justify?
40-102
The total heat content of a system is called enthalpy. Equation
H= E+PV E,P and V are state functions so enthalpy is also a state function.It is not possible to measure the enthalpy of a system in a given state.However change in enthalpy can be measured for achange in the state of system.

##### Question: 41
What do you mean by significant figures ? Give the rules for determining significant figures ?
41-102
Significant Figures:The combination of accurately known digits and the first doubtful digits during a measurement are known as as significant figures
Rules for determining significant figures:
1. All non-zero digits from '1' to '9' are significant for example in 36.473 m there are five significant figure
2. All zero between two non-zero digits are significant for example in y= 4.03 m there are three significant figures
3. The zero to the right of a decimal symbol and to the left of non-zero digits are not significant
4. All zero to the right of a decimal appears after non-zero digits are significant
5. In case of scientific notation the figures before the power of ten are significant
6. In case of addition and subtraction the result obtained is retained to the measurement which is least precise in the data
7. In case of multiplication and division the final result is retained to the measurement which contains the last number of significant figure
8. In case of rounding of non-significant figures the following rules should be followed.
• IF the dropping digits is less than '5' then it will be just ignored For example 863.73 is rounded to 863.7
• If the dropping digits is greater than '5' then the last retained digit is increased by '1' for example 8.76 is rounded of 8.8
• If the dropping digits is '5' and the last retained digits is even then it will remains uneffected. for example, 56.45 is rounded to 56.4
• If the dropping digits is '5' and the last retained and the last retained digits is add than it will be increased by '1' for example 46.35 is rounded to 46.4
##### Question: 42
How the distance between interference fringes will be affected if the distance between the slits in Young 's experiment is doubled.?
42-102
##### Question: 43
What is Scientific Notation .Explain ?
43-102
Writting number in power of ten or standard from N=M*10nis called scientific Notation.
Explanation:With the help of Scientific Notation, we can express very large number or small number very easily. A large or small number "N" can be expressed in term of a number "M" and a power of '10 '
N= M * 10n-------------------(1)
In equation 1 "M" represents a number whose first digit is non-zero digit. "n" represents the power of 10, which may be positive or negative
For example 150,000,000,000 m can be expressed in scientific notation as under
150,000,000,000 m = 1.5* 1011m
##### Question: 44
Define light year. How many meters are there in one light year?
[ Speed of light = 3x108ms-1)
44-102
Alight year is the distance light travels in one year.
Since
S = vt
or S = vt
S= (3x108ms-1)(365x24x60x60 s)
S= 9.46x 1015m
##### Question: 45
Give four parasitic adaptation of flat worms.
45-102
1. The epidermis is absent and there is formation of resistant cuticle for protection.
2. They have developed adhesive organs,such as sucker and hooks for attachment to the host.
3. There is degeneration of muscular and nervous system.
##### Question: 46
What role SI units have played in the development of science
46-102
With the development of science and technology, S.I units fulfill the serious need of for a commonly accept system of unit all over the world.
##### Question: 47
Write the main type of error.
47-102
There are two types of errors possible I n physical measurements.
1. Random error
2. Systematic error
##### Question: 48
Differentiate between Base Units and Derived Units.
48-102
Base Units:The units associated with the base quantities are called base units. Other units are derived from base units . There are meter, Kilogram, second, candela, mole, ampere, kelvin.

Derived Units:The units associated with the derived quantities are called derived units. SI units for measuring all other physical quantities are derived from the base and supplementary units. For example , newton, joule,watt and pascal are derived units.
##### Question: 49
Differentiate between the following? (a) Light year and year
49-102
1. Light Year:Light year is the unit of distance. It is defined as, " the distance travelled by light in vacuum in one year."
2. Year:Year is the unit of time. It is defined as the time interval in which the earth completes one revolution around the sun"
1 Year = 365.25 days
and
1 year = 365.25*24*3600 sec
1 year = 31557600 sec
##### Question: 50
Define Measurement, unit and Magnitude?
50-102
Measurement:The comparison of some thing with some standard is known as measurement.
Unit:The standard with which thing are compared is known as unit.
Magnitude:A number with proper unit is known as magnitude.
##### Question: 51
How many seconds are there in one year?
51-102
Now 1 year = 1x 365 days
1 year = 365x 1 days
1 year = 365x 24 hours
1 year = 8760 x 1 seconds
1 year = 3.1536x 107s
##### Question: 52
Define base units. Give one example.
52-102
Base Units: The units that describe base quantities are called base units.
##### Question: 53
Define and explain supplementary units?
53-102
The general conference on Weights and Measures has not yet classified certain unit of SI under either base or derived units. These SI units are called supplementary units.
Radian: The radian is the plane angle between two radii of a circle which cut off on the circumference an arc, equal I length to the radius. It is two dimensional angles.
Steradian: The Sterdian is the solid angle subtended at the center of the sphere by an area of its surface equal to the square of radius of the sphere. It is three dimensional angles.
##### Question: 54
Define Base, Derived, supplementary, Units ?
54-102
Base Units:The units of base quantities are known as base unit.
Base quantity: Symbol
Length l
Mass M
Time t
Electric current I
Temperature T
Derived Quantity:The unit of derived quantities are known as derived units. The derived units can be derived from base unit and supplementary units
Supplementary Units:The general conference on weight and measures has not yet classified certain units of the SI under either base units or derived units such SI Units are called supplementary units This class contains only two units of purely geometrical quantities which are place angle and the said angle.
1. Radian :It is the unit of plane angle. One radian represents a plane angle subtended at the center of a circle by on are of length equal to radius of the circle.
2. Steradian:Steradian is the unit for a solid angle in a three dimensional space steradian is defined as "the solid angle subtended at the center of a sphere by an area of its surface equal to the square of the radius of that sphere"
##### Question: 55
How many nanoseconds are there in 1 year?
55-102
As 1 year = 3.136x107 s
1 year = 3.1536x107 X1s
1 year =3.1536x107x109x10-9s
1 year =3.1536x107x10-9ns
1 year =3.1536x 1016ns
##### Question: 56
Define Physical Quantities ? Explain base quantities and derived quantities?
56-102
Physical Quantities:All the measurable quantities are known as physical quantities for example, speed, mass , force, velocity, momentum temperature etc
• Base Quantities:These are those physical quantities in term of which other physical quantities can be defined the base quantities can not be defined in term of other physical quantities.
Example of base quantities:These are the seven base quantities, which are given below.
1. Mass
2. Length
3. Time
4. Current
5. Temperature
6. Amount of substance
7. Luminous intensity
• Derived Quantities:Those physical quantities which can be derived from base quantities are known as derived quantities
Example of derived quantities:
Force, Work, Power, energy, momentum, torque, speed, acceleration etc are the example of derived physical quantities

##### Question: 57
Give two example of phylum platyhelminthes and Nematoda.
57-102
Phylum platyhelminthes includes Liver fluke and Planaria.
##### Question: 58
58-102
Radian and steradians are not the basic units of SI. These are the units of purely geometrical quantities i,e plane angle and solid angle respectively. The general conference on weight and measures has not yet classified there units under either base unit or derived units these are called supplementary units.
##### Question: 59
What are derived units? Explain.
59-102
The units associated with the derived quantities are called derived units. SI units for measuring all other physical quantities are derived from the base and supplementary units. For example , newton, joule,watt and pascal are derived units.
##### Question: 60
Define system of units ? Give the name of various system of unit?
60-102
System Units:A complete set of unit for all physical quantities is known as system of units .
Explanation:There are several system of unit For example
Foot - pound - system ( FPS)
Meter - kilogram -second system (MKS )
Centimetre - gram - second system (CGS )
But the most popular system id the system international (SI)
System International(SI):In 1960 on international committee agreed on a set of definitions and standards to describe the physical quantities. The system that was established is called system international (SI)
The system international is used throughout the world. Its unit are convenient for daily use .
The system international is build-up from three kinds of unit
• Base Unit
• Derived Units
• Supplementary Units
##### Question: 61
Discuss the assessment of uncertainty in the final result?
61-102
##### Question: 62
Define base quantities and units.
62-102
Base quantities: Base quantities are quantities on the basic of which other quantities are expressed.
##### Question: 63
Define derived units and write two example.
63-102
Derived units: The units used to measure derived quantities are called derived units.
##### Question: 64
Define the term error, uncertainty precision and accuracy in measurements?
64-102
Errors:The difference between measured value and actual value of a quantity is known as Error.
Uncertainty:An estimate of the possible range of an error is known as uncertainty. (OR)
The error which arises due to natural imperfections of the experimenter, the limitations of the apparatus and the changes in the environment during the measurement is known as uncertainty.
Precision:The measure of the consistency of measurements is known as precision. It requirements the magnitude of error in measurements.
Accuracy:The measure of correctness of a measurements is known as accuracy"
The Accuracy means to check how the measure values is closer to the actual value It is a relative is closer to the actual value.It is a relative error. it can be obtained by dividing the error with measured quantity The accuracy depends on the error is greater than smaller will be the accuracy of the measurement can be increased by taking several reading and then take their average
##### Question: 65
what is time period?
65-102
The time taken by vibrating body to complete its one vibration is called time period.
##### Question: 66
How many meters are there in one light year?
66-102
Since S= vt
S =ct
S = (3 x 108ms-1)(365x24x60x60 s)
S= 9.46x 1015m
##### Question: 67
Find the dimension of kinetic energy ?
67-102
##### Question: 68
Explain Server repetitive phenomena occuring naturally which could served reason able time stands?
68-102
Any phenomenon that repeats its after regular time intervals can be used as a time standard.
The several repetitive phenomenon occuring naturally which could served reasonable time standards are given below.
1. The motion of earth around the sun and its spin motion can be used as reasonable time standards
2. Revolution of mean around the earth can be used as reasonable time standards.
3. Characteristics vibration of crystals such as quartz crystal can be used as reasonable time standards
4. Some other repetitive phenomena which can be adopted to define a time standards are heart beat, human pulse rate radio active decay rate of some substance, changing of seasons change of shadow of an object in the sun light etc.
##### Question: 69
What is meant by coexistances.
69-102
Living with other human beigns in peace and harmony mutual peace and lvoe is claled coexistence
##### Question: 70
Deduce the dimensions of gravitational constant ?
70-102
##### Question: 71
What are base units name all of them?
71-102
The units associated with the base quantities are called base units. Other units are derived from base units . There are meter, Kilogram, second, candela, mole, ampere, kelvin.
##### Question: 72
Define international system of units.
72-102
The international system of units is a scientific method of expressing the magnitudes of quantities of important natural phenomana. There are seven base units in the system, from which other units are derived. This system was formarly called the meter-kilogram second (MKS) system.
##### Question: 73
What is unit
73-102
Once a standard is set for a quantity then it can be expressed in terms of that standard quantity. This standard quantity is called unit.
##### Question: 74
Find the base quantities involved in each of the following derived quantities:
74-102
work, Force
Work is derive from base quantities mass, length and time.
##### Question: 75
Give the drawbacks to use the period of pendulum as a time standard.
75-102
The value of time periods of a simple pendulum depends upon its length and gravitational acceleration. So, the following drawbacks will be observed.
• The value of g varies with altitudes
• Length of the pendulum varies due to the increase or decrease in temperature .
• Air resistance will affect the time period.

##### Question: 76
Define prefixes and write two examples.
76-102
Prefixes: Prefixes are the words or letters added before a unit and stand for the multiples or sub-multiples of that unit
##### Question: 77
Name several repetitive phenomenon occurring in nature which could serve as reasonable time standard.
77-102
Some of the natural phenomena that can be used as time standard are as follow:
1. The rotation of earth around the sun.
2. The revolution of earth .
3. The revolution of moon around the earth.
4. Atomic vibrations in crystals.
##### Question: 78
Define base and derived quantities.
78-102
Base Quantities are the quantities on the basis of which other quantities are expressed.
Examples: Length, mass time electric current, temperature. intensity of light and amount of substance are examples of base quantities.
##### Question: 79
What are two principal characteristics of an ideal standard?
79-102
An ideal standard has two principal characteristics.
1. It is accessible.
2. It is invariable.
##### Question: 80
which base quantities has units mole and kelvin
80-102
Mole: Mole is unit of base quantity "Amount of a substance"
##### Question: 81
What are supplementary units? Write their names.
81-102
The General Conference on Weights and Measure has not yet classified certain unit of SI under either base or derived units. Theses SI units are called supplementary units.
##### Question: 82
Define derived quantities and write the name of two derived quantities.
82-102
Derived quantities: Those physical quantities which are expressed in terms of base quantities are called the derived quantities.
##### Question: 83
Define basic units.
83-102
The units associated with the base quantities are called base units. Theses are meter, kilogram, second, ampere, kelvin, candela, mole.
##### Question: 84
Why do we find it useful to have two units for the amount of substance kilogram and mole?
84-102
Both units are used to describe the amount of the substance. Kilogram is used for macroscopic objects or for macroscopic behavior of the objects while mole is used for microscopic object or on microscopic scale when number of atoms or molecules are concerned.
##### Question: 85
what is the displacement of an obeject of an object in SHM when K.E and P.E are equal?
85-102
when K.E and P.E are equal then the displacement will be the half of amplitude of vibrating body.
##### Question: 86
Describe the structure of ripple tank
86-102
ripple tank consist of a rectangular tray having glass bottom and is placed nearly half meter above the surface of table
##### Question: 87
Write down four conventions for indicating units.
87-102
The convection for indicating units are as follows:
1. Full name of the unit does not begin with the capital letter even if named after a scientist e.g. Newton.
2. The symbol of unit named after a scientists has initial capital letter e.g. N for newton.
3. The prefix should be written before the unit without any spacee.g. 1x 10-6= µ m

4. Compound prefixes are not allowed. For example 1 µµF should be written as 1 pF.

##### Question: 88
How can you assess the uncertainty in the average value of many measurements?
88-102
To assess the uncertainty, we find the deviation of each measured value from the average value. The mean deviation is the uncertainty in the average value.
##### Question: 89
what is diffraction?
89-102
the bending or spreading of waves around the sharp edges or obstacles is called diffraction.
##### Question: 90
Draw a table for base units.
90-102
Base Quantity. Base units Symbol
Length Metre m
Mass Kilogram kg
Time ampere s
Electric Current Kelvin A
Thermodynamic Temperature Mole K
Amount of substance Candela mol
Luminous Intensity Second cd
##### Question: 91
How can we reduce random and systematic error?

91-102
Reduce random error: Repeating the measurement several times and taking an average can reduce the effect of random error.

Reduce systematic error: The systematic error can be reduced by comparing the instrument with another which is known to be more accurate and a correction factor is applied.
##### Question: 92
What type of blood vessels surrounds the alveoli?
92-102
Artery
##### Question: 93
What do you mean by scientific notation? Give an example.
93-102
The standard form to represent numbers using power of ten is called scientific notation. The accepted practice is that there should be only one non-zero digit left o decimal. For Example
The scientific notation of measurement 134.7 is 1.347 x 102.
##### Question: 94
Define meter and Kelvin.
94-102
Meter: One meter is the distance travelled by light in vacuum during a time of 1 /299, 792,458 seconds.
Kelvin: One kelvin is the fraction 1/273.16 of the thermodynamic temperature the triple point of water.
##### Question: 95
Define significant figures.
95-102
In any measurement, the accurately Known digits and the first doubtful digit are called the significant figures. For example, The number of significant figures in the measurement 02.59 are 3.
##### Question: 96
How can you define term wave?
96-102
A wave is disturbance in the medium which causes the particles of medium to undergovibratory motion
##### Question: 97
Name two major types of errors in measurement and also define them.
97-102
The major types of errors in measurement are Systematic Error and Random Error.

Systematic Errors:Systematic errors occurs when repeated measurements of a quantity give the same values under the same conditions.This error is due to poor calibration or zero error in the stop watch. This error can be removed by applying correction factor
##### Question: 98
Define the process of painting with one example.
98-102
It is structual adaptation for heat regulation in dogs. Painting is evaporative cooling in the respiratory tract for temperature regulation.
##### Question: 99
The period of simple pendulum is measured by a stop watch. What type of errors are possible in the time period?
99-102
The two types of errors are possible .
Random error which is due to the negligence or inexperience of a person at the time of starting and stopping the stopwatch.And systematic error which occurs due to the poor calibration of the instrument.
##### Question: 100
Give two adaptation of marine fish for its survival in cold environment.
100-102
These fishes have a thick layer of insulting fat called blubber which prevent excess heat loss from the body.
##### Question: 101
Define systematic errors. Explain how can we remove the effect of systematic errors?
101-102
Systematic Errors: Systematic errors occurs when repeated measurements of a quantity give the same values under the same conditions.
This error is due to poor calibration or zero error in the stop watch. This error can be removed by applying correction factor.
##### Question: 102
Define anhydrobiosis with an example
102-102
The ability to tolerate dehydration this process is called anhydrobiosis for example kangaroo rat a desert animal can tolerate dehydration without drinking water by feeding desert plants containing more carbohydrates which produce water of metabolism