Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
11. What is the Gaussian unit of kinematic viscosity?
[A] Henry
[B] Stokes
[C] poiseiulle
[D] Watt
Show Answer
Correct Answer: B [Stokes]
Notes:
The Gaussian unit of kinematic viscosity is stokes. Ten thousand stokes equal one square meter per second.
12. Which of the following represents the total momentum transferred to a surface by an electromagnetic wave?
[A] Total energy transferred/Speed of light
[B] Total energy transferred/ 2 x Speed of light
[C] 2 x Total energy transferred/Speed of light
[D] None of the above
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Correct Answer: A [Total energy transferred/Speed of light]
Notes:
If the total energy transferred to a surface in time t is U, then the magnitude of the total momentum delivered to this surface (for complete absorption) is U/c.
13. What do we call the distance between two consecutive compressions of a sound wave?
[A] Wave number
[B] Frequency
[C] Wavelength
[D] Amplitude
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Correct Answer: C [Wavelength]
Notes:
The distance between two consecutive compressions (C) or two consecutive rarefactions (R) is called the wavelength.
14. What is supersonic speed?
[A] When the speed of any object exceeds the speed of sound
[B] When the speed of any object exceeds the speed of light
[C] When the speed of any object exceeds 10000 m/s
[D] None of the above
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Correct Answer: A [When the speed of any object exceeds the speed of sound]
Notes:
When the speed of any object exceeds the speed of sound it is said to be travelling at supersonic speed. Bullets, jet aircrafts etc. often travel at supersonic speeds.
15. Which of the following is correct about compressions in sound wave?
[A] compressions are regions of low pressure and low density
[B] compressions are regions of high pressure and low density
[C] compressions are regions of high pressure and high density
[D] compressions are regions of low pressure and high density
Show Answer
Correct Answer: C [compressions are regions of high pressure and high density]
Notes:
Compressions are the regions where particles are crowded together and represented by the upper portion of the curve. Compressions are regions where density as well as pressure is high.
16. What is the process known as when substance converts from the solid to the vapour state directly?
[A] Vaporisation
[B] Sublimation
[C] Regelation
[D] None of the above
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Correct Answer: B [Sublimation]
Notes:
The change from solid state to vapour state without passing through the liquid state is called sublimation. Example: Dry ice (solid CO2).
17. Which of the following are Green house gases?
[A] Carbon dioxide
[B] Methane
[C] Nitrous oxide
[D] All of the above
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Correct Answer: D [All of the above]
Notes:
Some of the green house gases: carbon dioxide, methane, nitrous oxide, chlorofluorocarbon, tropospheric ozone.
18. Which of the following is true about an adiabatic wall?
[A] it allows flow of heat from one system to another
[B] it allows flow of particles from one system to another
[C] it does not allow flow of heat from one system to another
[D] None of the above
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Correct Answer: C [it does not allow flow of heat from one system to another]
Notes:
An adiabatic wall is an insulating wall (can be movable) that does not allow flow of energy (heat) from one to another.
19. What do we call the process taking place at constant pressure?
[A] Isochoric
[B] Isobaric
[C] Adiabatic
[D] Isothermal
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Correct Answer: B [Isobaric]
Notes:
The process taking place at constant pressure is called as Isobaric process.
20. Which of the following represents the Snell’s law?
[A] sine of angle of incidence/sine of angle of refraction = constant
[B] cosine of angle of incidence/cosine of angle of refraction = constant
[C] tangent of angle of incidence/tangent of angle of refraction = constant
[D] angle of incidence – angle of refraction = constant
Show Answer
Correct Answer: A [sine of angle of incidence/sine of angle of refraction = constant]
Notes:
The ratio of sine of angle of incidence to the sine of angle of refraction is a constant, for the light of a given colour and for the given pair of media. This law is also known as Snell’s law of refraction.
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