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Concepts Of Physics MCQ Edition [Volume 2]
Exam
Concepts Of Physics MCQ Edition [Volume 2]
Subject
Physics
Chapter
Heat Transfer

Concepts Of Physics MCQ Edition [Volume 2] · Physics · Heat Transfer

Newton's law of cooling represents a special case of

Newton's law of cooling represents a special case of

Options

  1. APlanck's law
  2. BKirchhoff's law
  3. CStefan's law
  4. DWien's displacement law

Correct answer

C. Stefan's law

Step-by-step solution

According to Stefan's law, the net rate of heat loss by radiation from a body at temperature TT in surroundings at temperature T0T_0 is given by P=eσA(T4−T04)P = e \sigma A (T^4 - T_0^4).

Let T=T0+ΔTT = T_0 + \Delta T, where the temperature difference ΔT\Delta T is very small compared to T0T_0.

Substituting this into Stefan's law:

P=eσA[(T0+ΔT)4−T04]P = e \sigma A [(T_0 + \Delta T)^4 - T_0^4]

P = e \sigma A T_0^4 \left[ \left(1 +\dfrac{\Delta T}{T_0}\right)^4 - 1\right]<br><br>UsingthebinomialexpansionforsmallΔTT0andneglectinghigher−orderterms:<br><br><br><br>Using the binomial expansion for small \dfrac{\Delta T}{T_0} and neglecting higher-order terms:<br><br>P \approx e \sigma A T_0^4 \left[1 + 4\dfrac{\Delta T}{T_0} - 1\right]<br><br><br><br>P \approx 4 e \sigma A T_0^3 \Delta T<br><br>Since<br><br>Since4 e \sigma A T_0^3isaconstantforagivenbodyandsurroundings,wegetis a constant for a given body and surroundings, we getP \propto \Delta T.

This is Newton's law of cooling, which states that the rate of heat loss is directly proportional to the temperature difference between the body and its surroundings. Thus, Newton's law of cooling is a special case of Stefan's law.
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