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10.2 , transmission of heat — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysics10.2 , transmission of heat1 Mark
MCQ
$Assertion :$ A hollow metallic closed container maintained at a uniform temperature can act as a source of black body radiation.
$Reason :$ All metals act as black bodies.
  • A
    If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
  • B
    If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
  • C
    If the Assertion is correct but Reason is incorrect.
  • ✓
    If both the Assertion and Reason are incorrect.
✓

Answer

Correct option: D.
If both the Assertion and Reason are incorrect.
d
A perfect black body is one which absorbs all heat radiations (whatever be the
wavelength) incident on it. No natural object is a perfect black body. Best approximations are lamp black and platinum black. Fery's black body is a double walled metallic sphere coated with lamp black on the inside and nickel on outside. It has a narrow opening opposite a conical projection inside.

$\therefore $ Both Assertion and Reason are incorrect

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