Medium MCQ +4 / -1 PYQ · JEE Mains 2020

A heat engine is involved with exchange of heat of 1915 J, – 40J, + 125 J and –Q J, during one cycle achieving an efficiency of 50.0%. The value of Q is

  1. A 980 J Correct answer
  2. B 40 J
  3. C 400 J
  4. D 640 J

Solution

$\eta$ = <span style="display: inline-block;vertical-align: middle;"> <div style="text-align: center;border-bottom: 1px solid black;"> Work done</div> <div style="text-align: center;"> Heat supplied </div> </span> <br><br>$\Rightarrow$ $\frac{1}{2}$ = $\frac{1915-40+125-Q}{1915+125}$ <br><br>$\Rightarrow$ $\frac{1}{2}$ = $\frac{2000-Q}{2040}$ <br><br>$\Rightarrow$ 2040 = 4000 – 2Q <br><br>$\Rightarrow$ 2Q = 1960 <br><br>$\Rightarrow$ Q = 980 J

About this question

Subject: Physics · Chapter: Thermodynamics · Topic: Zeroth and First Law

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