300+ TOP Unit of Measurement Interview Questions – Answers

1. What Is Meant By Units?

The reference standard for measurement is called unit.

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.

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.

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.

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.

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.

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.

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.

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.

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.

11. What Is Meant By Length?

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

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.

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.

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.

15. Which Is The Unit Used To Express The Distance Of Stars From The Earth?

• Parsec (Parallactic second)
• 1 parsec = 3.08 * 10¹⁶m

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

17. Which Are The Indirect Methods To Measure Very Large Distance?

1. Angular distance method
2. Parallax method
3. Reflection Method

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.

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.

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.

21. Mention Some Applications Of Reflection Methods?

1. To determine the thickness of a piece of matter.
2. RADAR (Radio detection and ranging), to determine the distance of an aeroplane from radar station.
3. SONAR (Sound Navigation and Ranging), to determine distance of a submarine, in non – destructive, mechanical testing of materials.

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.

23. What Is A Decibel (db)?

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

24. What Is Dead Time?

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

25. What Is Bomb Calorimeter?

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

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.

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.

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.

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.

30. What Is Force?

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

31. Define Interia?

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

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.

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.

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.

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

Decibel.

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.

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.

38. What Is Emissive Power?

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

39. What Is Chronotron?

A device used for measuring the time interval between events.

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.

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

Volt.

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

Barn.

43. Barn Is Equal To?

10^-24 cm²

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

Bel.

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

Hertz.

46. An Altimeter Is Used For Measuring What?

Altitude.

47. What Is Unit Of Power?

Watt.

48. Cresco Graph Is Used To Measure The?

Rate of plant growth.

49. Who First Introduced The Modern Concept Of Mass?

Isaac Newton.

50. What Is Unit Of Magnetic Flux?

Newton per metre.

51. What Is Hertz?

Hertz is the unit of frequency.

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

Calorie.

53. What Is Calorie?

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

54. What Is Smallest Unit Of Length?

Fermi.

55. What Is ‘ampere’ Per Metre?

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

56. What Is Unit Of Illumination?

Lux.

57. What Is The Mass Of A Proton?

1.672 * 10 ^-27kg.

58. Time Period Of Ultrasonic Wave?

10 ^-5 s.

59. What Is The Unit Of Electromotive Force?

Volt.

60. Who Formulated The Laws Of Motion?

Issac Newton.

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.

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

Zero.

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

They have a relative speed of zero.

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

About 190 km / hour.

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.

66. Which Unit Is Used To Measure Supersonic Speed?

Mac.

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

Robert Boyle.

68. What Is The Unit Of Length?

Metre.

69. What Is Unit Of Pressure?

Pascal.

70. How Is The Electricity For Domestic Purpose Measured?

Kilo watt hour (kWh).

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

Ampere.

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

Farad.

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

Electric flux.

74. What Is Kelvin?

Unit of temperature interval.

75. What Is The Unit Of Potential?

Volt.

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

Inductance.

77. What Is Horse Power?

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

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

Andres Celsius.

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

Erg.

80. What Is A Fahrenheit?

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

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

Egypt.

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

-39 ^o C.

83. What Is Curie?

It is unit of measurement of radioactivity.

84. What Is Electric Charge Of An Electron?

1.6 * 10¹⁹ Coulomb.