1. What is the SI unit of frequency?
BPSC 2018–19 | RRB Group D 2018
Answer: Hertz (Hz)
2. What is the SI unit of electric charge?
SSC JE 2019 | RRB NTPC 2021
Answer: Coulomb (C)
3. What is the SI unit of work?
SSC MTS 2021 | SSC CGL 2022
Answer: Joule (J)
4. In which unit is electric current expressed?
RRB ALP 2018 | RRB Group D 2018
Answer: Ampere (A)
5. What is the SI unit of electric power?
Answer: Kilowatt (kW)
6. What is the SI unit of power of a lens?
MPPCS | SSC MTS
Answer: Dioptre
7. What is the SI unit of wavelength of light?
Answer: Angstrom (Å)
8. What is the SI unit of acceleration?
SSC CGL 2018
Answer: m/s²
9. What is the numerical value of a physical quantity called?
Answer: Magnitude
10. What is the SI unit of mass?
Answer: Kilogram (kg)
11. What is the SI unit of luminous intensity?
Answer: Candela (cd)
12. What is the SI unit of amount of substance?
Answer: Mole (mol)
13. What is the SI unit of plane angle?
Answer: Radian
14. What is the SI unit of solid angle?
Answer: Steradian
15. What is the SI unit of pressure?
Answer: Pascal (Pa)
16. What is the SI unit of resistance?
Answer: Ohm (Ω)
17. What is the SI unit of electric field intensity?
Answer: Newton/Coulomb (N/C)
18. What is the SI unit of momentum?
Answer: kg·m/s
19. What is the SI unit of force?
Answer: Newton (N)
20. What is the SI unit of energy?
Answer: Joule (J)
21. What is the formula for density?
Answer: Density = Mass / Volume
22. What is the formula for velocity?
Answer: Velocity = Displacement / Time
23. What is the formula for speed?
Answer: Speed = Distance / Time
24. What is the formula for acceleration?
Answer: Acceleration = Change in velocity / Time
25. What is the formula for work?
Answer: Work = Force × Displacement
26. What is the formula for frequency?
Answer: Frequency = 1 / Time period
27. What is the formula for momentum?
Answer: Momentum = Mass × Velocity
28. What is the formula for power?
Answer: Power = Work / Time
29. What is the formula for pressure?
Answer: Pressure = Force / Area
30. What is the formula for impulse?
Answer: Impulse = Force × Time
31. What is the SI prefix for 10⁻¹⁵?
Answer: Femto (f)
32. What is the SI prefix for 10⁹?
Answer: Giga (G)
33. What is the SI prefix for 10⁶?
Answer: Mega (M)
34. What is the SI prefix for 10³?
Answer: Kilo (k)
35. What is the SI prefix for 10⁻⁶?
Answer: Micro (µ)
36. What is the SI prefix for 10⁻⁹?
Answer: Nano (n)
37. How many microns are there in one metre?
UPPCS | SSC CGL
Answer: 10⁶ microns
38. One horsepower is approximately equal to how many watts?
SSC CPO 2020 | RRB Group D 2022
Answer: 746 watts
39. One nautical mile is equal to how many metres?
SSC CGL 2019
Answer: 1852 metres
40. One light year is approximately equal to?
Answer: 9.46 × 10¹⁵ metres
41. One Angstrom is equal to?
Answer: 10⁻¹⁰ metre
42. One parsec is approximately equal to?
Answer: 3.086 × 10¹⁶ metres
43. One calorie is approximately equal to?
Answer: 4.186 joules
44. One electron volt is approximately equal to?
Answer: 1.602 × 10⁻¹⁹ joule
45. Which waves require a medium for their propagation?
Answer: Mechanical waves
46. Which waves do not require a medium for propagation?
Answer: Electromagnetic waves
47. Sound waves are what type of waves?
Answer: Mechanical waves
48. Sound waves are generally what type of mechanical waves?
Answer: Longitudinal waves
49. Light waves are what type of waves?
Answer: Electromagnetic transverse waves
50. Which is the highest-frequency electromagnetic wave?
SSC CHSL 2019
Answer: Gamma rays
51. Which waves are used in radar systems?
SSC CHSL 2019
Answer: Microwaves
52. Cathode rays are a beam of what?
SSC CHSL 2019
Answer: Electrons
53. What is the frequency range of audible sound for humans?
Answer: 20 Hz to 20,000 Hz
54. What are infrasonic waves?
Answer: Sound waves having frequency below 20 Hz
55. What are ultrasonic waves?
Answer: Sound waves having frequency above 20,000 Hz
56. What is the frequency of ultrasonic waves?
REET | RRB JE | SSC GD
Answer: More than 20,000 Hz
57. When the speed of an object exceeds the speed of sound, what is it called?
SSC JE 2021
Answer: Supersonic speed
58. What sound intensity is considered most suitable for humans?
Answer: About 45 decibels
59. Sound intensity above approximately 80 dB is called what?
Answer: Noise
60. What is the angle between the reflected ray and the normal called?
Answer: Angle of reflection
61. When light passes through the centre of curvature of a spherical mirror, what is the angle between incident and reflected rays?
Answer: 0°
62. How many colours compose white light?
Answer: Seven
63. What is the splitting of white light into its constituent colours called?
Answer: Dispersion of light
64. Why does the clear sky appear blue?
Answer: Scattering of light
65. What phenomenon is responsible for the formation of a rainbow?
Answer: Refraction, reflection and total internal reflection
66. What phenomenon causes the shining of a diamond?
Answer: Total internal reflection
67. What principle is used in optical fibre?
Answer: Total internal reflection
68. What phenomenon causes the formation of a mirage?
Answer: Total internal reflection
69. Which mirror is used by dentists?
RRB NTPC 2021 | RRB Group D 2022
Answer: Concave mirror
70. Which mirror is commonly used as a rear-view mirror in vehicles?
Answer: Convex mirror
71. Which mirror is used in solar furnaces?
Answer: Concave mirror
72. Which mirror is used in street lights?
Answer: Convex mirror
73. Which colour has the longest wavelength in visible light?
Answer: Red
74. Which colour has the shortest wavelength in visible light?
Answer: Violet
75. Which colour has a longer wavelength than yellow light?
SSC Steno 2019
Answer: Orange
76. Which electromagnetic waves are used in thermal imaging?
Answer: Infrared radiation
77. Which electromagnetic waves are used in remote sensing?
Answer: Infrared radiation
78. Which electromagnetic waves are used in medical imaging and treatment?
Answer: X-rays / appropriate electromagnetic radiation depending on application
79. Which electromagnetic waves are used for radio, television and radar communication?
Answer: Radio waves
80. Which radiation can cause skin cancer due to excessive exposure?
RRB Group D 2022
Answer: Ultraviolet radiation
81. Which electromagnetic waves are used by a TV remote control?
SSC CGL 2019
Answer: Infrared waves
82. Which electromagnetic waves have frequencies roughly from 3 kHz to 300 GHz?
SSC CHSL 2021
Answer: Radio waves
83. Why does the sky appear black from outer space?
Answer: There is no atmosphere to scatter sunlight.
84. What is the approximate speed of light in vacuum?
Answer: 3 × 10⁸ m/s
85. What energy conversion takes place in a battery?
SSC CGL 2019 | SSC JE 2020
Answer: Chemical energy → Electrical energy
86. On which principle does an electric motor work?
RRB Group D 2022
Answer: Magnetic effect of electric current
87. Which device converts mechanical energy into electrical energy?
RRC Group D 2022
Answer: Dynamo
88. Which device converts AC into DC?
SSC CHSL 2017
Answer: Rectifier
89. Into what form of energy does a photocell convert light energy?
SSC MTS 2017
Answer: Electrical energy
90. What energy conversion occurs in a windmill/turbine?
SSC CGL 2019
Answer: Mechanical energy → Electrical energy
91. What energy conversion occurs in a steam engine?
SSC MTS 2017
Answer: Thermal energy → Mechanical/Kinetic energy
92. What energy conversion takes place in a solar cell?
Answer: Light energy → Electrical energy
93. What energy conversion occurs in an electric bulb?
Answer: Electrical energy → Light + Heat energy
94. What energy conversion occurs in a loudspeaker?
Answer: Electrical energy → Sound energy
95. Who formulated the Universal Law of Gravitation?
Answer: Isaac Newton
96. Who gave the Three Laws of Motion?
Answer: Isaac Newton
97. Who formulated the Theory of Relativity?
Answer: Albert Einstein
98. Who explained the photoelectric effect?
Answer: Albert Einstein
99. Who proposed electromagnetic theory?
Answer: James Clerk Maxwell
100. Who discovered the Raman Effect?
Answer: C. V. Raman
101. Who discovered the Doppler Effect?
Answer: Christian Doppler
102. Who formulated the laws of electrostatic attraction?
Answer: Charles-Augustin de Coulomb
103. Who proposed Quantum Theory?
Answer: Max Planck
104. Who formulated Ohm's Law?
Answer: G. S. Ohm
105. Who formulated the principle of flotation?
Answer: Archimedes
106. Who proposed the Big Bang Theory?
Answer: Georges Lemaître
107. Who formulated Pascal's Principle?
Answer: Blaise Pascal
108. Who formulated the law of conservation of electric charge?
Answer: Benjamin Franklin
109. Who proposed the photo-electromagnetic wave theory?
Answer: James Clerk Maxwell
110. Who proposed the theory of interference of light?
Answer: Thomas Young
111. Who proposed the wave theory of light?
Answer: Christiaan Huygens
112. Who is credited with the concept of three laws of planetary motion?
SSC CGL, 2021
Answer: Johannes Kepler
113. Which principle explains the thrust produced by rocket engines and jet engines?
SSC JE, 2021; SSC CPO, 2022
Answer: Newton's Third Law of Motion
114. Who first introduced the concept of electric field?
2021; RRB Group D, 2022
Answer: Michael Faraday
115. Which law is used to find the direction of magnetic field around a current-carrying conductor?
SSC CPO, 2022
Answer: Maxwell's Corkscrew Rule
116. What does the Big Bang Theory explain?
SSC CHSL, 2021
Answer: Origin of the Universe
117. Which law gives the force between two stationary point charges?
SSC MTS, 2021; SSC CGL, 2021
Answer: Coulomb's Law
118. Who discovered the phenomenon of electromagnetic induction?
Answer: Michael Faraday
119. Who discovered and named the science of electromagnetism?
SSC CGL, 2019
Answer: André-Marie Ampère
120. Who formulated the Theory of Relativity?
RPF SI, 2019; SSC CGL, 2019
Answer: Albert Einstein
121. Which instrument measures altitude/height of an aircraft?
SSC CHSL, 2021
Answer: Altimeter
122. Which instrument measures electric current?
Answer: Ammeter
123. Which instrument measures sound intensity?
Answer: Audiometer
124. Which instrument measures wind speed?
Answer: Anemometer
125. Which instrument measures atmospheric humidity?
RRB Group D, 2018; SSC MTS, 2022
Answer: Hygrometer
126. Which instrument measures specific gravity?
Answer: Hydrometer
127. Which instrument measures underwater sound signals?
SSC Steno, 2020, 2021
Answer: Hydrophone
128. Which instrument measures atmospheric pressure?
RRB/SSC various
Answer: Barometer
129. Which instrument measures temperature?
RRB Group D, 2018; SSC MTS, 2022
Answer: Thermometer
130. Which instrument measures electrical potential difference?
SSC MTS, 2020; RRB NTPC, 2021
Answer: Voltmeter
131. Which instrument detects acoustic signals underwater?
Answer: Hydrophone
132. Which instrument measures the purity of milk by measuring relative density?
SSC CHSL, 2020
Answer: Lactometer
133. Which instrument measures extremely high temperatures?
UPPCS; SSC MTS, 2020
Answer: Pyrometer
134. Which instrument measures earthquake intensity?
UPPCS/SSC CGL
Answer: Seismograph
135. Which instrument measures the speed of motor vehicles?
Answer: Speedometer
136. Which instrument measures viscosity of liquids?
Answer: Viscometer
137. Which instrument measures thermal radiation?
Answer: Radio radiometer
138. Which instrument is used to detect brain tumours and heart defects?
Answer: Ultrasonoscope
139. Which instrument measures electrical resistance?
Answer: Ohmmeter
140. Which instrument measures rainfall?
Answer: Udometer
141. Which instrument detects lies?
Answer: Polygraph
142. Which instrument measures the intensity of an earthquake?
Answer: Seismograph