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MHT CET 202625 AprilEvening Shift
Exam
MHT CET
Year
2026
Date
25 April
Shift
Evening Shift
Subject
Physics
Chapter
Thermodynamics

MHT CET 2026 · 25 April · Evening Shift · Physics · Thermodynamics

Let _1 be the efficiency of a Carnot engine at T_H = 547^ ^ C and...

Let η1\eta_1 be the efficiency of a Carnot engine at T_H = 547^{}^{\circ}\text{C} and T_C = 247^{}^{\circ}\text{C} while η2\eta_2 is the efficiency at T_H = 847^{}^{\circ}\text{C} and T_C = 147^{}^{\circ}\text{C}. If η1=x41η2\eta_1 = \dfrac{x}{41}\eta_2, the value of xx is

Options

  1. A2424
  2. B2525
  3. C2020
  4. D2222

Correct answer

A. 2424

Step-by-step solution

The temperatures for the first Carnot engine in Kelvin are:

TH1=547∘C+273=820 KT_{H₁} = 547^{{}^{\circ}}\text{C} + 273 = 820\text{ K}

TC1=247∘C+273=520 KT_{C1} = 247^{{}^{\circ}}\text{C} + 273 = 520\text{ K}

The efficiency η1\eta_1 is given by:

η1=1−TC1TH1=1−520820=1−2641=1541\eta_1 = 1 - \dfrac{T_{C1}}{T_{H₁}} = 1 - \dfrac{520}{820} = 1 - \dfrac{26}{41} = \dfrac{15}{41}

The temperatures for the second Carnot engine in Kelvin are:

TH2=847∘C+273=1120 KT_{H₂} = 847^{{}^{\circ}}\text{C} + 273 = 1120\text{ K}

TC2=147∘C+273=420 KT_{C2} = 147^{{}^{\circ}}\text{C} + 273 = 420\text{ K}

The efficiency η2\eta_2 is given by:

η2=1−TC2TH2=1−4201120=1−38=58\eta_2 = 1 - \dfrac{T_{C2}}{T_{H₂}} = 1 - \dfrac{420}{1120} = 1 - \dfrac{3}{8} = \dfrac{5}{8}

Given the relation η1=x41η2\eta_1 = \dfrac{x}{41}\eta_2, substituting the values of η1\eta_1 and η2\eta_2:

1541=x41×58\dfrac{15}{41} = \dfrac{x}{41} \times \dfrac{5}{8}

15=5x815 = \dfrac{5x}{8}

x=15×85=24x = \dfrac{15 \times 8}{5} = 24

Answer: 2424
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