JEE Main 2022 (Online) 24th June Morning Shift | Heat and Thermodynamics Question 155 | Physics

A Carnot engine whose heat sinks at 27$$^\circ$$C, has an efficiency of 25%. By how many degrees should the temperature of the source be changed to increase the efficiency by 100% of the original efficiency?

Increases by 18$$^\circ$$C

Increases by 200$$^\circ$$C

Increases by 120$$^\circ$$C

Increases by 73$$^\circ$$C

JEE Main 2022 (Online) 24th June Morning Shift

MCQ (Single Correct Answer)

-1

Two metallic blocks M₁ and M₂ of same area of cross-section are connected to each other (as shown in figure). If the thermal conductivity of M₂ is K then the thermal conductivity of M₁ will be :

[Assume steady state heat conduction]

JEE Main 2022 (Online) 24th June Morning Shift Physics - Heat and Thermodynamics Question 125 English

10 K

8 K

12.5 K

2 K

JEE Main 2021 (Online) 31st August Evening Shift

MCQ (Single Correct Answer)

-1

Two thin metallic spherical shells of radii r₁ and r₂ (r₁ < r₂) are placed with their centres coinciding. A material of thermal conductivity K is filled in the space between the shells. The inner shell is maintained at temperature $$\theta$$₁ and the outer shell at temperature $$\theta$$₂($$\theta$$₁ < $$\theta$$₂). The rate at which heat flows radially through the material is :-

$${{4\pi K{r_1}{r_2}({\theta _2} - {\theta _1})} \over {{r_2} - {r_1}}}$$

$${{\pi {r_1}{r_2}({\theta _2} - {\theta _1})} \over {{r_2} - {r_1}}}$$

$${{K({\theta _2} - {\theta _1})} \over {{r_2} - {r_1}}}$$

$${{K({\theta _2} - {\theta _1})({r_2} - {r_1})} \over {4\pi {r_1}{r_2}}}$$

JEE Main 2021 (Online) 31st August Evening Shift

MCQ (Single Correct Answer)

-1

A mixture of hydrogen and oxygen has volume 500 cm³, temperature 300 K, pressure 400 kPa and mass 0.76 g. The ratio of masses of oxygen to hydrogen will be :-

3 : 8

3 : 16

16 : 3

8 : 3

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