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MHT CET202120 Sep 2021Morning ShiftPhysicsThermal Properties of MatterActual

A black rectangular surface of area ' A ' emits energy ' E ' per second at 27^ C . If length and breadth is reduced to (1 / 3)^ rd of its initial value and temperature is raised to 327^ C then energy emitted per second becomes

Options

  1. A20 E 9
  2. B8 E 9
  3. C16 E 9
  4. D4 E 9

Correct answer

C. 16 E 9

Step-by-step solution

aligned & E = AT ^4 & E ^ = A ^ T ^ 4 & ~A = L B & A ^ = L 3 B 3 = A 9 & ~T =27^ C =300 ~K & ~T ^ =327^ C =600 ~K & E ^ E = A ^ A ( T ^ T )^4= 1 9 (2)^4 & E ^ = 16 E 9 aligned

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