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  • Question
  • Hot water is poured simultaneously in four metallic tumblers painted outside with different paints. After some time the water will be found to have cooled most in the tumbler painted.


  • Options
  • A. rough white
  • B. rough black
  • C. shining white
  • D. shining black

  • Correct Answer
  • rough black 

    Explanation

    Black surfaces are good emitters of heat. If the black surface is rough too, the emitting will be better. Shinning surfaces reflect black radiation . So if the black surface is also shining the effectiveness of emitting heat is lessened.


  • Physics problems


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    • 1. For accurate scientific work, temperatures are often measured by

    • Options
    • A. mercury thermometers
    • B. alcohol thermometers
    • C. platinum resistance thermometers
    • D. thermoelectric thermometers
    • Discuss
    • 2. When a bullet is fired from a gun

    • Options
    • A. the gun moves forward
    • B. the gun jumps up
    • C. the gun does not move
    • D. the gun recoils with the same momentum as the bullet
    • Discuss
    • 3. Radian is used to measure

    • Options
    • A. Temperature
    • B. Intensity of Flame
    • C. Angle
    • D. Solid Angle
    • Discuss
    • 4. Radiocarbon is produced in the atmosphere as a result of

    • Options
    • A. collision between fast neutrons and nitrogen nuclei present in the atmosphere
    • B. action of ultraviolet light from the sun on atmospheric oxygen
    • C. action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere
    • D. lightning discharge in atmosphere
    • Discuss
    • 5. A bucket of water is hung from a spring balance. A piece of iron is suspended in the water without touching the sides or touching the bottom of the the bucket. The reading of the spring balance

    • Options
    • A. will increase
    • B. will decrease
    • C. does not change
    • D. varies with the increase of depth of the immersion of the iron piece
    • Discuss
    • 6. Electrical Arcing occurs when
    • Discuss
    • 7. Which planet has the lowest density?

    • Options
    • A. Earth
    • B. Jupiter
    • C. Saturn
    • D. Neptune
    • Discuss
    • 8. The p wave of a normal Electrocardiogram indicates

    • Options
    • A. atrial depolarization
    • B. Ventricular repolarization
    • C. atrial repolarization
    • D. Ventricular depolarization
    • Discuss
    • 9. Which statement best describes an igneous intrusion?

    • Options
    • A. Igneous intrusion for when ice crystals splash into lava
    • B. Magma is injected into surrounding rock forming an igneous intrusive
    • C. Magma is exported to an open area and forms iron
    • D. Magma explodes to the surface and forms a smooth outer layer of rock
    • Discuss
    • 10. Sound waves cannot travel through

    • Options
    • A. Gas
    • B. Liquid
    • C. Vacuum
    • D. Solid
    • Discuss


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