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Thermodynamics — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsThermodynamics1 Mark
MCQ
A Carnot's engine is made to work between $200^{\circ} \mathrm{C}$ and $0^{\circ} \mathrm{C}$ first and then between $0^{\circ} \mathrm{C}$ and $-200^{\circ} \mathrm{C}$. The ratio of efficiencies of the engine in the two cases is
  • ✓
    $1.73: 1$
  • B
    $1: 1.73$
  • C
    $1: 1$
  • D
    $1: 2$
✓

Answer

Correct option: A.
$1.73: 1$
In first case $\eta_1=1-\frac{T_2}{T_1}=1-\frac{(273+0)}{(273+200)}=\frac{200}{473}$
In second case $\eta_2=1-\frac{(273-200)}{(273+0)}=\frac{200}{273}$
$\Rightarrow\frac{\eta_1}{\eta_2}=\frac{1}{\left(\frac{473}{273}\right)}=1: 1.73$

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