## Unit of Measurement Interview Questions & Answers

1. Question 1. What Is Meant By Units?

The reference standard for measurement is called unit.

2. Question 2. What Is The Need For Measuring A Physical Quantity?

The measurement of physical quantity is necessary because without it, we can’t study the characteristic features of the problem.

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4. Question 3. What Is Fundamental Physical Quantity?

There are seven physical quantities i.e. length, mass, time, electric current, temperature, light intensity, and amount of substance are called fundamental physical quantities.

5. Question 4. What Is Metrology?

Metrology is defined by the ‘International Bureau of Weights and Measures’ (BIPM) as the science of measurement embracing both experimental and theoretical determinations at any level of uncertainty in the feild of Science and Technology.

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7. Question 5. What Is The Common System Of Unit For Describing Measurements?

The common systems are the C.G.S. system, the F.P.S system, the M.K.S system, and the S.I. system.

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9. Question 6. What Is The C.g.s System?

It is based upon three basic units, the centimeter, the gram and the second for the length, the mass and the time measurements respectively.

10. Question 7. What Is The F.p.s System Or The British System?

It is based on three basic units, the foot, the pound and the second for the length, the mass and the time, respectively.

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12. Question 8. What Is M.k.s System?

It is based upon the three basic units, the metre, the kilogram and the second for the length, the mass and the time respectively.

13. Question 9. What Is S.i System?

This system is now internationally accepted. It stands for the system International d’ units. These are the metre (m) for length, the kilogram (kg) for mass, the second (s) for the time, Kelvin (k) for temperature, ampere (A) for the current, candela (cd) for light intensity and mole (mol) for amount of substance. This system is used by almost all the countries of the world.

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15. Question 10. S.i System Is Used All Over The World. Why?

All the units are well defined and easily reproducible at the entire place. All the units do not change with time, place, pressure, temperature etc., because they depend upon some fundamental property of the atom. In S.I system the unit of energy (all forms) is joule and watt as the unit of power.

16. Question 11. What Is Meant By Length?

The distance of separation between two points in space is called length.

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18. Question 12. What Is The Relation Between The Magnitude And The Unit Of A Physical Quantity?

A particular physical quantity expressed in a bigger unit has a smaller magnitude and vice versa.

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20. Question 13. Why Do We Need Indirect Methods Of Measurement Of Certain Distances?

When it is not possible to measure a particular distance by its direct comparison with a certain standard, we need indirect methods. We need indirect methods when the distance to be measured is either too large or too small.

21. Question 14. Which Units Are Used For Measuring Distance Of The Order Of Astronomical Distance?

• Light year; 1 light year = 9.46 * 1015 metres
• Astronomical units ( A.U ) ; 1 A.U= 1.496 * 1011 metres , One Astronomical Unit ( A.U ) is the distance between the earth and the sun.
22. Question 15. Which Is The Unit Used To Express The Distance Of Stars From The Earth?

• Parsec (Parallactic second)
• 1 parsec = 3.08 * 1016m
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24. Question 16. Which Units Are Used For Measuring Atomic Or Molecular Distance?

• Micron. 1 Micron = 10-6
• Mill micron. 1 Mill micron = 10-9
• Angstrom Unit ( A ). 1 A = 10-10
• Fermi. (f) 1 f = 10-15
25. Question 17. Which Are The Indirect Methods To Measure Very Large Distance?

1. Angular distance method
2. Parallax method
3. Reflection Method
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27. Question 18. What Is The Term Parallax Means?

The apparent shift of a body with respect to another, with the shift of eye is called parallax. The nearer body always appears to move in a direction opposite to that of the eye.

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29. Question 19. How Can We Determine The Distance Of The Moon From The Earth By Reflection Method?

To find out the distance between moon and earth, we send a radar signal from earth which will be reflected from the surface of moon back to the receiver. If the time between sending and receiving of the signal be “ t ” and “ v ” be the velocity of the signal, the distance between moon and the earth is v * t / 2. A radar signal travels with the velocity of light i.e. equal to 3 * 108 m/s.

30. Question 20. Define The Term Mass?

Mass of an object is the quantity of matter contained in the objects. It is the basic property of matter. It is a constant quantity i.e. it does not depend upon temperature, pressure and location of the object in space.

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32. Question 21. Mention Some Applications Of Reflection Methods?

1. To determine the thickness of a piece of matter.
3. SONAR (Sound Navigation and Ranging), to determine distance of a submarine, in non – destructive, mechanical testing of materials.
33. Question 22. What Is The Decibel Scale?

The difference in amplitude between the quietest sounds and sounds so loud they hurt is almost too great to write down in numbers. The decibel scale is an example of a logarithmic scale.

34. Question 23. What Is A Decibel (db)?

A unit used to express the intensity of a sound wave. It is measured on a logarithmic scale.

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36. Question 24. What Is Dead Time?

The time interval immediately following a stimulus during which it is insensitive to another stimulus.

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38. Question 25. What Is Bomb Calorimeter?

A type of calorimeter measuring the heat evolved by the combustion of a fuel.

39. Question 26. What Is Astronomical Unit (a.u)?

A unit or distance in astronomy in the solar system. It is equal to approximately 1.496 * 1011 metre. That is the mean distance of sun from earth.

40. Question 27. Define Weight Of A Body?

Weight is the force with which a body is pulled towards the earth. It is the product of the mass and the acceleration due to gravity at that place.

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42. Question 28. Distinguish Between And Weight?

Mass: It is the quantity of matter contained in the object. It is a constant quantity. It is measured in kilogram. It is a scalar quantity. It is measured by the physical balance.

Weight: It is the force with which the body is pulled towards the earth. It is not a constant quantity. It is measured in newton. It is a vector quantity. It is measured by a spring balance.

43. Question 29. What Will Be The Weight Of An Object Of Mass In Kilogram In Space Away From Earth?

It is zero, because g = 0 in space.

44. Question 30. What Is Force?

It is some agency which tends to change the motion of an object, either its state or its direction.

45. Question 31. Define Interia?

The tendency of an object to oppose any alteration in its state of rest or a uniform motion is called interia.

46. Question 32. What Is Meant By Base Units?

The units of length, mass, time, temperature, electric current, light intensity and amount of substance are called base units.

47. Question 33. What Are Natural Units?

Systems of units based on arbitrary unit values, formalized as standards, some unit values occur naturally in science, systems of units based on these are called natural units.

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49. Question 34. Which System Of Measurement Was Standardized First?

The metric system was standardized in France between 1791 and 1795, the imperial system in England 1824.

50. Question 35. The Intensity Of The Second Is Measured In Which Units?

Decibel.

51. Question 36. What Is Ampere?

Unit of electric current, one ampere current is equal to the flow of one coloumb of charge per second. It is nearly equal to the flow of 6 * 1018 electrons / second.

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53. Question 37. What Is Anemometer?

An instrument used for measuring the speed of the wind or any other flowing fluid. The simple anemometer is made up of a number of cups or blades.

54. Question 38. What Is Emissive Power?

The total energy emitted from unit surface area of body per second.

55. Question 39. What Is Chronotron?

A device used for measuring the time interval between events.

56. Question 40. Time Taken By Light To Reach From The Sun To The Earth In 8 Minutes And 20 Seconds. The Speed Of Light Is 3 * 10 8 M/s. If The New Unit Of Length Is Taken Such That Speed Of Light Is 1, What Is The Distance Between The Sun And Earth In New Units?

500 new units.

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58. Question 41. What Is The Unit Used To Measure Electromotive Force?

Volt.

59. Question 42. What Is The Unit Of Area For Measuring The Cross Section Of Nuclei?

Barn.

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61. Question 43. Barn Is Equal To?

10-24 cm2

62. Question 44. What Is The Logarithmic Unit Expressing The Ratio Of Power, Voltage, Current Or Sound Intensity?

Bel.

63. Question 45. What Is The Name Of The Unit Of Frequency Equal To 1012 Hz?

Hertz.

64. Question 46. An Altimeter Is Used For Measuring What?

Altitude.

65. Question 47. What Is Unit Of Power?

Watt.

66. Question 48. Cresco Graph Is Used To Measure The?

Rate of plant growth.

67. Question 49. Who First Introduced The Modern Concept Of Mass?

Isaac Newton.

68. Question 50. What Is Unit Of Magnetic Flux?

Newton per metre.

69. Question 51. What Is Hertz?

Hertz is the unit of frequency.

70. Question 52. What Was The Name Of The Unit Of Heat Now Replaced By The Joule?

Calorie.

71. Question 53. What Is Calorie?

Unit of heat equal to the amount needed to raise the temperature of 1 gm. water through 1oC.

72. Question 54. What Is Smallest Unit Of Length?

Fermi.

73. Question 55. What Is ‘ampere’ Per Metre?

It is the S.I unit of magnetic field strength.

74. Question 56. What Is Unit Of Illumination?

Lux.

75. Question 57. What Is The Mass Of A Proton?

1.672 * 10 -27kg.

76. Question 58. Time Period Of Ultrasonic Wave?

10 -5 s.

77. Question 59. What Is The Unit Of Electromotive Force?

Volt.

78. Question 60. Who Formulated The Laws Of Motion?

Issac Newton.

79. Question 61. How Many Motions Are Caused When A Ball Is Thrown?

When a ball is thrown it moves in two ways at the same time, forwards at a constant speed and downwards due to gravity of the earth.

80. Question 62. What Will The Weight Of A Body At The Centre Of The Earth?

Zero.

81. Question 63. What Will Be The Speed Of Two Cars Racing At The Same Speed?

They have a relative speed of zero.

82. Question 64. What Will Be The Terminal Velocity For A Sky Diver Falling In A Flat Position?

83. Question 65. What Is Terminal Velocity?

A falling object from the sky accelerates as it falls. Friction between the object and the air, acts against the gravity. Air resistance increases as the object falls faster and when it equals the force of gravity, the object stops accelerating and falls at a steady speed.

84. Question 66. Which Unit Is Used To Measure Supersonic Speed?

Mac.

85. Question 67. Who Discovered The Relation Between Gas Pressure And Volume?

Robert Boyle.

86. Question 68. What Is The Unit Of Length?

Metre.

87. Question 69. What Is Unit Of Pressure?

Pascal.

88. Question 70. How Is The Electricity For Domestic Purpose Measured?

Kilo watt hour (kWh).

89. Question 71. What Is The S.i Unit Of Current?

Ampere.

90. Question 72. What Is The S.i Unit Of Capacitance?

91. Question 73. What Is Called The Measure Of Number Of Field Lines Penetrating A Surface?

Electric flux.

92. Question 74. What Is Kelvin?

Unit of temperature interval.

93. Question 75. What Is The Unit Of Potential?

Volt.

94. Question 76. What Is Measured By The S.i Unit Called A Henry?

Inductance.

95. Question 77. What Is Horse Power?

Unit of power, equal to work performed at the rate of 550 ft. lb / sec.

96. Question 78. Which Swedish Scientist Had A Temperature Scale Named After Hime?

Andres Celsius.

97. Question 79. What Is The Absolute Unit Of Work In Cgs System?

Erg.

98. Question 80. What Is A Fahrenheit?

Temperature scale on which melting point of ice is 320 F and the boiling point of water is 2120F.

99. Question 81. In Which Country The Beam Balance Was First Used?

Egypt.

100. Question 82. What Is Freezing Point Of Mercury In Celsius Scale?

-39 o C.

101. Question 83. What Is Curie?