Practice Light heat thermodynamics wave sound optics oscillation - general science mcq Online Quiz (set-2) For All Competitive Exams
Q-1) A man standing between two parallel hills fires a gun and hears two echoes, one 2.5 s and the other 3.5 s after the firing. If the velocity of sound is 330 m$s^{–1}$, how long will it take him to hear the third echo?
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Q-2) The normal temperature of human body on the Kelvin scale is
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Q-3) The safest temperature for keeping food fresh in a refrigerator is
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Q-4) The simple harmonic motion of a particle is given by y = 3 sinω + 4 cosω. Which one of the following is the amplitude of this motion?
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Q-5) The number of images of an object placed between two parallel mirrors is
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Q-6) Power of Sunglass is
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Q-7) Suppose a tunnel is dug along a diameter of the earth. A particle is dropped from a point, a distance h directly above the tunnel, the motion of the particle is
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Q-8) If a liquid is heated in condition of weightlessness, the heat is transmitted through
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Convection is not possible in weightlessness. So the liquid will be heated through conduction.
Q-9) Material A has a critical angle $i_A$, and material B has a critical angle $i_B$ ($i_B > i_A$). Then which of the following is true?
- Light can be totally internally reflected when it passes from B to A
- Light can be totally internally reflected when it passes from A to B
- Critical angle for total internal reflection is $i_B – i_A$
- Critical angle between A and B is $sin^{-1}({sini_A}/{sini_B})$
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iB > iA or sin-1 $(1/{µ_B})$ > sin-1 $(1/{µ_A})$ or µA > µB
Hence medium A is denser and B is rarer.
Total internal Reflection: When the object is placed in an optically denser medium. and if the incident angle is greater than the critical angle then the ray of light gets reflected back to the originating medium.
For critical angle (α) from medium A to B, ${_Bµ_A}$
${_Bµ_A}$ = $1/{sin α}$ or sin α = $1/{_Bµ_A}$ = ${µ_B}/{µ_A}$
⇒ sin α = $1/{sin i_B}$ x ${sin i_A}/1$
⇒ α = sin-1 $[{sin i_A}/{sin i_B}]$
Q-10) When pressure on piece of ice is increases its melting point
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Q-11) For the myopic eye, the defect is cured by
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Q-12) What is the decibel level of sound produced by two persons in conversation?
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Q-13) In SONAR, we use
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Q-14) An endoscope is a
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Q-15) The atmosphere exerts enormous pressure on us. But, we do not feel it because
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Q-16) Power of accommodation of eye implies
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Q-17) The small ozone layer on the top of stratosphere is crucial for human survival as it –
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The ozone layer in stratosphere absorbs ultraviolet radiation in sun rays which are harmful. For human being.
Q-18) The minimum height of a plane mirror to see the full size image of a person is equal to
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Q-19) What is the effect of humidity on sound waves when humidity increases?
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The velocity of sound = $√{γRT}/M$
When water vapour is present in air average molecular weight of air decreases and hence velocity increases.
Q-20) Red light signal is used as a danger signal because
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