9th Class Physics Chapter 1 Short Questions with Answers Solved

Question: 1

Define atomic physics.

Answer: 1

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Which deals with the study of structure and properties of atom.

Question: 2

Define electricity and magnetism.

Answer: 2

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The branch of physics which deals with the study of charges at rest and to motion their effects and their relationship with magnetism

Question: 3

What is international system of units?

Answer: 3

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A world-wide system of measurements is known as international system of units(SI).In SI,the units of seven base quantities are meter,kilogramme,second,ampere,kelvin,candela and mole.

Question: 4

What is nuclear physics.

Answer: 4

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Which deals with the properties and behaviour of nuclei and particles within the nuclei

Question: 5

Define Derived Quantities.

Answer: 5

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The quantities that are expressed in terms of base quantities are called derived quantities.For Example speed area etc.

Question: 6

What is law of conversation of momentum?

Answer: 6

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The momentum of an isolatedsystem of two or more than two interacting bodies remains constant

Question: 7

Define Heat.

Answer: 7

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Branch of physics which deals with the nature of heat, modes of transfer and effects of heat.

Question: 8

Define Sound.

Answer: 8

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The branch of physics which deals with the physical aspects of sound waves, their production properties and applications.

Question: 9

Define Plasma physics.

Answer: 9

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Which deals with the stydy of production properties of the ionic state of matter, the forth state of matter.

Question: 10

Why is the use of zero error necessary in a measuring

Answer: 10

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Zero error is necessary in measuring instrument to obtain an extremely correct value by means of applying zero correction.

Question: 11

Define physics

Answer: 11

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Physics:

In physics, we study matter, energy and theirinteraction. The laws and principles of physics help us to understand

Question: 12

Estimate your age in seconds

Answer: 12

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Age in years= 15

Age in seconds=15 x 365 x24 x60x60

=473040000 second

Question: 13

Waht do you understand by zero error of measuring instrument?

Answer: 13

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Zero error means the minimum error found in a measuring instrument.

Question: 14

Define physics.

Answer: 14

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Branch of science which deals with matter, energy and their mutual relationship. there are many branches of physics.

Question: 15

Why is the use of zero error necessary in a measuring instrument?

Answer: 15

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Zero error is necessary in measuring instruments because it helps us to check the instrument we are using wheathercorrect or wrong.

Question: 16

Write two important parts of ernier callipers.

Answer: 16

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A vernier callipers consists on two parts. One part is main scale and other part is known as vernier scale. Main scale is attached with fixed jaw on which centimeters and millimeters are marked. The other part, vernier scale, is connected by a movable jaw which is divided into 10 equal divisions.

Question: 17

Define optics/light.

Answer: 17

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The branch of physics which deals with the study of physical aspect of light . Its properties working and use of optical instrument.

Question: 18

What is meant by vernier constant?

Answer: 18

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the vernier constant is defined as the difference between one main scale division and one vernier scale division

Question: 19

Describe two situations in which force of friction is needed?

Answer: 19

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1-We cannot write if there would be no friction between pen and paper

2- Friction enables us to walk on the ground. we cannot run on a slippery ground. A slippery ground offers very less friction.

Question: 20

What is meant by least count

Answer: 20

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The smallest reading that can be taken by using any measuring instrument is called its least count.

Question: 21

What are physical quantities.

Answer: 21

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All measurable quantities are called physical quantities. For example mass, length and temperature.

Question: 22

Define Mechanics.

Answer: 22

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It is the study of motion of objects its causes and effects.

Question: 23

Describe two advantages of physics in daily life.

Answer: 23

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Pulleys that make it easy to left heavy loads.

Question: 24

What is the use of physical balance

Answer: 24

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A physical balance is used in the laboratory to measure the mass of various objects by comparison.

Question: 25

What is meant by scientific notation.

Answer: 25

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A way of writing number s by using the power of ten or prefixes and there is only one nonzero digit before the decimal is called scientific notation. Example a number 62750 can be expressed as 6.275 x 10^4.

Question: 26

What is least count of digital vernier callipers.

Answer: 26

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Digital vernier callipers has greater precision than mechanical vernier callipers. Least count of digital vernier calipers is 0.01 mm.MM.

Question: 27

What are prefixes? Also give example.

Answer: 27

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There are some numbers which are very large or small .to write them using some suitable multiples or submultiples is called prefixes. Example: Centi, Milli, mega

Question: 28

What is meant by Vernier Constant

Answer: 28

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The least count of the vernier callipers is also called the vernier constrant. Vernier callipers is a measuring instrument in which the difference between one small division on main scale division and one vernier scale division is 0.1 mm. It is called least count (LC)of the vernier callipers.

Question: 29

What do you understand the by the zero error of measuring instrument

Answer: 29

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any error in the measuring instrument that can effect the reading is called zero error

Question: 30

Describe scientific notation? Give an example.

Answer: 30

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Scientific Notation:

In scientific notation a number is expressed as some power of ten multiplied by a number between 1 and 10. For example, a number 62750 can be expressed as 6.2750 x 10⁴

Question: 31

What role SI units have played in the development of science?

Answer: 31

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With the development in field of science and technology,the need for a commonly acceptable system of units was seriously felt all over the world particularly to exchange scientific and technical information.This need was fulfilled by SI units.

Question: 32

Define physical balance.

Answer: 32

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A physical balance is used in laboratory to measure the mass of various objects by comparison. Its least count is 10 mg

Question: 33

Define zero error and zero correction.

Answer: 33

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Zero error If a measuring instrument does not measure the correct value of measurement, then this error is called zero error.

Question: 34

Differentiate between base units and derived units.

Answer: 34

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Base units: The units that describe base quantities are called base units e.g. kg.

Question: 35

Define physical quantities and explain its types

Answer: 35

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physical Quantities: All measurable quantities are called physical quantities.

Examples: length mass, time, temperature etc.

Characteristics: A physical quantity possesses at least two characteristics:

Numerical magnitude, A unit in which it is measured

Question: 36

Define prefixes and give examples.

Answer: 36

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Prefixes:

The words or letters added before a unit and stand for the multiples or sub-multiples of that unit are known as prefixes . For example Kilo, mega, milli, micro, etc.

Question: 37

How can we measure the volume of and irregular shaped solid

Answer: 37

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Take some water in a graduated measuring cylinder.

Note the volume vi of water in the cylinder.

Tie the solid with a thread

Lower the solid into the cylinder till it is fully immersed in water.

Note the volume vf of water

Volume of the solid will be vf-vi

Question: 38

Define geophysics.

Answer: 38

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Which deals with the study of internal structure of the earth.

Question: 39

What is screw gauge, why is it used?

Answer: 39

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A screw gauge is an instrument used to measure small lengths with accuracy greater than a vernier callipers it is also called micrometer screw gauge.

Question: 40

Define Base Quantities.

Answer: 40

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Seven physical quantities which form the foundation for other physical quantities are called base quantities.

Question: 41

What do you know aboutphysical balance?

Answer: 41

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Physical Balance:

Physical balance is a modified type of beam balance used to measure small masses by comparison with greater occuracy.

Question: 42

Write the numbers given in scientific notation.

Answer: 42

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In scientific notation.

0.0000000016g=1.6*10g

Question: 43

What do you mean by zero error and zero correction?

Answer: 43

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Zero Error:

If the zero line of vernier scale is not coincidingwith main scale the zero error exits

Question: 44

What is Screw Gauge

Answer: 44

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Screw gauge: A screw gauge is an instrument that is used to measure small lengths with accuarc greater than vernier callipers. It is also called as micrometer screw gauge.

Question: 45

What is Internal system of units?

Answer: 45

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The worldwide acceptable system of measurements is called international system of units. It was adopted in the 11th General conference on wight and measures held in Paris in 1960

Question: 46

What is meant by Least Count of a screw gauge

Answer: 46

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Least count of screw gauge. The minimum measurement can measure a screw gauge is called least count of screw gauge.

Question: 47

Write 6000 km and 3800 km in standard form.

Answer: 47

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In standard form: 3800km=3.8*10km

Question: 48

What is significant figure?

Answer: 48

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Significant Figure:

All the accurately known digits and the first doubtful digit in an expression are called significant figures.

Question: 49

What is the importance of physics in our daily life

Answer: 49

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Laws and principles of physics help us to understand nature.

The rapid progress in science during the recent years has become possible due to discoveries and inventions in the field of physics. The technologies are the applications of scientific principles. Most of the technologies of our modern society throughout the world are related to physics. For example, car is made on the principles of mechanics and a refrigerator is based on principles of thermodynamics. In our daily life there are lots of applications of physic For example in electrical appliances (air conditioners, washing machine), means of transport (cars, aeroplanes), means of communication (radio, T.V, Telephone) etc.

Question: 50

What is stopwatch? Write the least count of mechanical stopwatch

Answer: 50

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Stopwatch: stopwatch is an instrument which is use to measure time interval of an event.

Question: 51

Differentiate between lever balance and electronic balance lever Balance:

Answer: 51

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A lever balance consists of a system of levers. When lever is lifted placing the object in one pan and standard masses on the other pan, the pointer of the lever system mover.

Question: 52

What do you understand by zero error of measuring instrument

Answer: 52

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Zero error means the minimum error found in a measuring instrument.

Question: 53

Write in standard form 384000000m and 0.00045s.

Answer: 53

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384000000 m

Question: 54

Write the importance of physicsin our daily life

Answer: 54

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Physic plays an important role in our daily life For example, office equipments, electricity is widely used everywhere, domestic appliancesmachines used in industry etc. Work on the basic law and principles of physics.

Question: 55

Define Screw gauge.

Answer: 55

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Screw Guage:

Screw guage is an instrument used to measure small lengthswith occuracygreater than a vernier calliper. It is also called micrometer screw gauge

Question: 56

What is electronic balance

Answer: 56

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Electronic balance is a device which is used to measure the mass of objects. It comes in different rangers i.e. mg, g,kg. Electronic balance is the most sensitive balance.

Question: 57

Define scientific notation and express 0.00580 in scientific notation.

Answer: 57

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Scientific notation: A way to express a given number as some power of ten mulltiplied or by prefixes by a number between 1 and 10 is called scientific notation.

Example: 0.00580

Question: 58

What is the use of meter rod

Answer: 58

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A metre rod is a length measuring instrument which can use to measure the length of an object r distance between two points with an accuracy of 1min.

Question: 59

Convert 12 years into seconds.

Answer: 59

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Days in one years = 365 days

Question: 60

Differentiate between electronic balance and physical balance

Answer: 60

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Electronic balance: Electronic balance is the most precise instrument for the measurement of mass.

The least count of electronic balance is 0.001g or mg

Question: 61

Estimate your 14 years age in seconds

Answer: 61

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total days in one year =14 years

Total days in 14 years 365 = dasys

= 14*365

=5110 days

Question: 62

When the zero error of screw guage will be positive

Answer: 62

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Zero error will be positive if zero circular scale is behind the index line. In this case, mutiply the number of divisions of the circular scale that has not crossed the index line with the least count of screw gauge to find zero error,

Question: 63

Least count of vernier callipers.

Answer: 63

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The vernier constant is defined as the difference between one main scale division and one vernier scale division.

Question: 64

Define the term light.

Answer: 64

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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 means something that can be seen using the eye, as opposed to invisible" things that cannot be seen.

Question: 65

Differentiate between positive zero Error and Negative zero Error

Answer: 65

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Positive Zero Error: Zero error will be positive if zero line of the vernier scale is on the right side of the zero the main scale.

Question: 66

Define electricity and magnetism

Answer: 66

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The branch of physics which deals with the study of charges at rest and in motion, their effects and their relationship with magenetism

Question: 67

Write four names of laboratory safety equipments.

Answer: 67

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A laboratory must have following safety equipments.

Question: 68

Define unit and what is International system of units.

Answer: 68

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Unit: A standard quantity needed for measuring unknown quantities is called unit.

Question: 69

Write twoi names of measuring instruments.

Answer: 69

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Names of measuring instruments are

Question: 70

What is digital stopwatch

Answer: 70

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Mechanical Stopwatch: A mechanical stopwatch can measure time interval upto minimum 0.1 second

A mechanical stopwatch showes reading through

During measuring reading may be a human error in reading

The least count of mechanical stopwatch is 0.1 second.

Question: 71

How many divisions are there on vernier scale

Answer: 71

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Vernier scale having 10 divisions over is such that each of division is 0.9 mm.

Question: 72

What are prefixes

Answer: 72

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Prefixes: The words or letters added before a unit and stand for multiples or sub-multiples of that unit are known as prefixes.

Question: 73

Define optics

Answer: 73

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The branch of physics which deals with the study of physical aspect of light Its properties. working and use of optical instruments.

Question: 74

Why a Screw Gauge measures more accurately than Vernier Callipers

Answer: 74

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Least count of Vernier calipers is 0.1 mm and least count of screw gauge is 0.01mm. Thus measurements taken by micrometer screw gauge are the most precise.

Question: 75

How do we need to measure extremely small intervals of time

Answer: 75

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In nature, there are so many phenomenon which vary with respect to the extremely small interval of time and for their experimental measurement we need to measure extremely small intervals of time.

Question: 76

Define least Count and also wirte least count of meter rod

Answer: 76

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Least Count: The smallest reading that can be taken by using any measuring instrument, is called its least count.

Question: 77

What is international system of units

Answer: 77

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The worldwide acceptable system of measurments is called international system of units.It was adopted in the 11th General Conference on weight and measures held in paris in 1960

Question: 78

How to use digital stop watch

Answer: 78

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The digital stop watch starts indicate the time lapsed as the start/stop button is pressed.

When start/stop button is pressed again, it stop and indicates the time interval recorded by it between start and stop of an event.

A reset button retroes its initial zero setting

Question: 79

When the zero error of screw gauge will be negative

Answer: 79

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Zero error of screw gauge will be negative if zero of circular scale has crossed the index line. In the case, the zero correction will be positive.

Question: 80

Write down the formula to calculate the least count of screw gauge.

Answer: 80

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Formula of least count is

Question: 81

A chocolate wrapper is 6.7cm long and 5.4 cm wide. calculate its area up to reasonable number of significant figures.

Answer: 81

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Length of chocolate wrapper 6.7cm

Question: 82

What do you mean by unit and system of unit

Answer: 82

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A standard quantity needed for measuring unknow quantities is know as unit

Question: 83

Define measuring cylinder and write its uses

Answer: 83

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Measuring cylinder: A measuring Cylinder is a glass or transparent plastic cylinder. Measuring cylinder has a scale along its length that indicate the volume in mills lite

Question: 84

What is meant by significant fique's

Answer: 84

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Significant figuers: All the digits that are known accurately and one estimated (doubtful) digit are called significant figures.

Question: 85

Define stop watch. What is L.C of mechanical stopwatch

Answer: 85

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The instrument used to calculate the time interval of an event is called stop watch. L.C of mechanical stopwatch = 0.1 second.

Question: 86

Define science and describe how science was divided into various branches.

Answer: 86

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The knowledge gained through observations and experimentations is called science. The word science is derived from the Latin word scientia" which means knowledge. Science was divided into various branches initially as described below.

Question: 87

Writer down rules to find the significant digits.

Answer: 87

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Rule to find the significant digits: Digits other than zero are always significant. i.e 27 has 2 significant digits and 275 has 3 significant digits

Zero between significant digits are also significant .e.g. 2705 has 4 significant digits.

Zeros after decimal point are significant. e.g 275.00 has 5 significant digits.

Question: 88

Define Kinemaics

Answer: 88

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Kinematics is the study of motion of an object without discussing the causes of motion.

Question: 89

How is stop watch used

Answer: 89

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A mechanical stopwatch has a knob that is used to wind the spring that powers the watch.

This kind can also be used as a start-stop and reset button

The watch starts when the knob is pressed onece.

When pressed second time, it stops the watch

The third press brings the needle back to zero position.

Question: 90

Find the number of significant figures in 100.8s and express in scientific notation

Answer: 90

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The number of significant figures in 100.8s is 4.

Question: 91

Define least count of screw gauge

Answer: 91

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Least count of screw gauge can also be found by dividing pitch of screw on number of divisions on circular scale i.e. 0.01mm or 0.01cm

Question: 92

Why is the use of zero error necessary in a measuring instrument

Answer: 92

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We use zero error in an instrument to get accurate reading.

Question: 93

What are measuring instruments

Answer: 93

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Measuring Instruments: Measuring instrument are used to measure various physical quantities such as length, mass, time, volume etc. Measuring instruments used around 1300 AD were quite crude. On the other hand, digital clocks and watches used now-a-days are highly reliable and accurate.

Question: 94

Find the base quantities involved in each of the following derived quantities

Answer: 94

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speed, volume, force, work

Question: 95

Explain the construction and use of metre rule and measuring tape.

Answer: 95

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Metre rule is a length measuring instrument and is commonly used in laboratories to measure length of an object or distance between two points.

Construction: It is one metre long which is equal to 100 cm. Each centimetre is divided into 10 small divisions called millimeter (mm). Thus one millimeter is the smallest reading on metre rule.

Question: 96

Pick out the base units in the following:

Answer: 96

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Base Unit: Kilogramme, mole, ampere, metre, Kelvin.

Question: 97

Find the number of significant figures in 0.00580km

Answer: 97

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Significant figures: 0.00580km the first two zero are not significant. They are used to space the decimal point. The digit 5,8 and the final zero are significant thus there are three significant figures.

Question: 98

Define physics and explain its branches.

Answer: 98

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physics: The branch of science which deals with the study of matter, energy and their mutual relationship is called physics.

Question: 99

Define nuclear physics

Answer: 99

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The branch of physics which deals with the properties and properties of atoms.

Question: 100

What is meant by significant figures of a measurement

Answer: 100

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In any measurement all accurately know digits and first doubtful digit are called significant figures.

Question: 101

Enlist the main branches of physics.

Answer: 101

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Mechanic, Heat thermodynamics, Atomic physics, Nuclear physics . plasma physics, Light, sound, Geophysics, Electricity and magnetism.

Question: 102

What is meant by pitch of screw gauge

Answer: 102

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A thimble has a threaded spindle inside it. As the tumble completes one rotation, the spindle moves 1 mm along the index line. The distance between consecutive threads on the spindle is 1mm. This distance is called pitch of screw gauge.

Question: 103

How is precision related to the significant figures in a measured quantity

Answer: 103

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More significant figures mean greater precision. For example two students measure the length of a book 18.42 cm and 18.425cm respectively with a vernier calliper and screw gauge respectively. The measurement 18.425 =cm is more precision becasue it has greater significant figures/

Question: 104

Give constructtion and use of a vernier Callipers

Answer: 104

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An accuracy greater than Imm can be obtained by using instruments such as Vernier Callipers.

An instrument which can length correct upto 0.1mm is called Vernier Calliper.

Question: 105

Give characteristics of physical quantities.

Answer: 105

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There are two characteristics of physical quantities

A Physical quantities of have magnitude

A physical quantitites have a suitable unit in which it is measured

Question: 106

What is difference between base quantities and derived quantities also give example

Answer: 106

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Base Quantities: The quantities on the base of which other quantities are expressed are called base quantities.

Example: There are seven base quantities Length, mass, time, electric currrent, intensity of light, temperature, amount of substance.

Question: 107

Define atomic physic

Answer: 107

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The branch of physics which deals with the study structure and properties of atoms.

Question: 108

What is meant by multiple and sub multiples

Answer: 108

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A unit can be increased or decreased by multiplying or dividing with 10 or some suitable power of 10.A positive power of 10 is called multiple and negative power of 10 is called sub multiples.

Question: 109

What is meant by pitch of screw gauge give its value

Answer: 109

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The distance between two consecutive threads on a spindle of a screw guge is called pitch Its value is 1mm.

Question: 110

What is the function of balancing screw in a physical balance

Answer: 110

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Balancing screws in a physical balance is used to bring the pointer at zero position.

Question: 111

Write the use of prefixes

Answer: 111

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Some quantities are either very large or very small prefixes are used to express very large or very small quantities. It makes these quantities to be express and understand esaily.

Question: 112

What role SI unit has play in the development of science

Answer: 112

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The SI unit are internationally acceptable units. They are very helpful to exchange scientific and technical information. They have brought consistency and uniformity in measurements and calculations by different scientist in different part of the world.

Question: 113

What is screw gauge, why is it used

Answer: 113

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A screw gauge is an instrument used to measure small lengths with accuracy greater than a vernier callipers it is also called micrometer screw gauge

Question: 114

Why do we study physics

Answer: 114

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Laws and principles of physics help us to understand nature Rapid progress in science during recent hears is due to discoveries and inventions in physics.

Question: 115

What are the advantages of vernier calliper over meter rule

Answer: 115

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Vernier calliper can measure up to 0.1mm i.e up to one tenth of millimeter whereas meter rule can measure up to 1mm.

Question: 116

What is andromeda

Answer: 116

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Andromeda is one of the billions of galaxier nearest nearest to our mikly way galaxy.

Question: 117

How numbers do are rounded off

Answer: 117

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There are some rules to round of the numbers.

If the last digit is less than 5, then if is simply dropped. For example 1.943 is rounded

If the last digit is greater than 5, then the digit on its left side is increased by one for example rounded

If the last digit is 5, then it is rounded to nearest even number. For example 1.35 is rounded to

Question: 118

Which one of following two instruments is more precise and why

Answer: 118

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Least count of vernier caallipers is 0.1 cm, and L.C of screw guage is 0.01mm so screw guage is more precise than vernier callipers because screw guage can take small reading more accurately.

Question: 119

What is meant by scientific notation

Answer: 119

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A way of writing numbers by using the power of ten or prefixes and there is only one non-zero digit before the decimal is called scientific notation. For example a number can be expressed a similarly the standard form of.

Question: 120

Define base quantities

Answer: 120

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Base Quantities: Base quantities are the quantities on the basis of which other quantities are expressed

Question: 121

What is important of physics in our daily life

Answer: 121

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The rapid progress in science during the recent yeard has become possible due to discoveries and inventions in the field of physics. For example, A car is made on the principles of mechanics and refrigerator is based on the principle of thermodynamics Similarly, the means of commuincation such as radio TV, Telephone, Computer are result of application of physics

Question: 122

Define scientific notation. Describe. it with examples.

Answer: 122

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Scientific Notation: In scientific notation a number is expressed as some power of ten multiplied by a number between 1 to 10 A simple but scientific way to write large or small numbers is to express them is some power of ten.

The Moon is 384000000 metres away from the Earth. Distance of the moon form the Earth can also be expressed as 3.84*10m. This form of expressing a number is called the standard form or scientific notation. This saves writing down or interpreting large numbers of zeros.

Question: 123

What is least count of digital Vernier calipers

Answer: 123

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Digital vernier callipers has greater precision than mechanical vernier callipers Least count of digital vernier callipers is 0.01mm

Question: 124

What is meant by prefixes

Answer: 124

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Prefixes: Prefixes are the words or letters added before a unit and stand for the multiples or submultiples of that unit

Question: 125

Define Scientific notation

Answer: 125

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Scientific notation: A way to express a given number as some power of ten multiplied or by prefixes by a number between is called scientific notation

between 1 and 10 is called scientific notation

Question: 126

Define Physical quantities.

Answer: 126

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All measurable quantities are called physical quantities such as length,mass,time and temperature.

Question: 127

Define sound

Answer: 127

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The branch of physics which deal with the physical aspects of sound waves their production properties and application

Question: 128

What is digital stopwatch.

Answer: 128

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Mechanical stopwatch: A mechanical stopwatch can measure a time interval up to minimum 0.1 second

A mechanical stopwatch shows reading through needles

During measuring reading may be a human error in reading

The least count of mechanical stopwatch is 0.1 second

Question: 129

Name the two scales of vernier calliper.

Answer: 129

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There are two scales in vernier callipers.

Main scale, Vernier scale

Question: 130

Why do we need to measure extremely small interval of time.

Answer: 130

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In physics most of the physical quantities are related to time like speed. velocity, acceleration etc. So to measure a quantity with great precision we need to measure extremly small interval of time.

Question: 131

Write four names of laboratory safety equipments

Answer: 131

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A laboratory must have following safety equipment's

Waste disposal basket
Fire extinguisher
Fire alarm
First aid box

Question: 132

Name five prefixes most commonly used.

Answer: 132

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There are prefixes most commonly used centi (c), milli. (m), kilo (k), mega (m), giga (g) micro (u)

Question: 133

Define the term light

Answer: 133

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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 means something that can be seen using the eye as opposed to invisible things that cannot be seen

Question: 134

What is Hubble space telescope

Answer: 134

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Hubble space telescope orbits around earth. It provided information about astronomic planets and galaxies.

Question: 135

What is the difference between Biological sciences and physical sciences

Answer: 135

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Biological Sciences: The branch of natural philosophy in which we study about living things is called biological sciences.

Question: 136

Define physical balance

Answer: 136

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A physical balance is used in laboratory to measure the mass of varous objects by comparison Its least count is 10mg.

Question: 137

Write down the formula to calculate the least count of screw gauge

Answer: 137

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Formula of least count is

least count=pitch of the screw gauge/no. of divisions on circular scale

Question: 138

Define geo physics.

Answer: 138

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The branch of physics which deals with the study of internal structure of the earth.

Question: 139

What do you understand the by the zero error of measuring instrument.

Answer: 139

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Any error in the measuring instrument that can effect the reading is called zero error
Zero error may be positive or negative
If the an instrument measured more then zero error will be positive
If an instrument measured less then zero error will be negative
The measured value will be less or more than the actual value

Question: 140

What is the function of balancing screws in a physical balance

Answer: 140

140-143

Balancing screw are used to equalize the pans when the balance is empty.

Question: 141

Writer the name of laboratory safety equipments.

Answer: 141

141-143

The laboratory safety equipments are following

Waste disposal basket, Fire extinguisher, Fire alarm. First Aid box. Sand and water buckets, Fire blanket to put off fire.

Question: 142

What role SI units have played in the development of science

Answer: 142

142-143

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: 143

Write down rules to find the significant digits

Answer: 143

143-143

Rule to find the significant digits: Digits other than zero are always significant has 2 significant digits and 275 has 3 significant digits

Zero between significant digits are also significant e.g 2705 has 4 significant digits

Zero after decimal point are significance e,g 275.00 has significant digits

Physics Chapters

9th Class Chapter 1 Physics Short Questions

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