JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 25 February 2021, Shift 2, Physics Q25

Question 25 of 90 in this shift, Physics question 25 of 30, Section B.

A reversible heat engine converts one-fourth of the heat input into work. When the temperature of the sink is reduced by 52 K, its efficiency is doubled. The temperature in Kelvin of the source will be ____________.

Official answer

208

NTA final key.

Chapter: Thermodynamics
Topic: Heat Engines and Refrigerators
Idea tested: Carnot Efficiency Limit

Same idea in other shifts

Asked 15× in all

8 Apr 2023, Shift 2 · Q34Work done by a Carnot engine operating between temperatures $127^\circ$ C and $27^\circ$ C is 2 kJ. The amount of heat transferred to the…EasySingle correct
12 Apr 2023, Shift 1 · Q38An engine operating between the boiling and freezing points of water will have A. efficiency more than 27%. B. efficiency less than the…MediumOther
25 Jul 2022, Shift 2 · Q45Let $\eta_1$ is the efficiency of an engine at $\mathrm{T_1}$ = 447°C and $\mathrm{T_2}$ = 147°C while $\eta_2$ is the efficiency at…EasySingle correct
28 Jul 2022, Shift 1 · Q37A Carnot engine has efficiency of 50%. If the temperature of sink is reduced by $40^\circ$ C, its efficiency increases by 30%. The…MediumSingle correct
30 Jul 2022, Shift 2 · Q7A Carnot engine is operating between the two reservoirs of temperature 227 $^\circ$ C and 127 $^\circ$ C respectively. If the engine…EasySingle correct
24 Jun 2022, Shift 1 · Q47A 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…MediumSingle correct
24 Jun 2022, Shift 2 · Q35A Carnot engine takes 5000 kcal of heat from a reservoir at $727^{\circ}C$ and gives heat to a sink at $127^{\circ}C$ . The work done by…EasySingle correct
26 Jun 2022, Shift 1 · Q37The efficiency of a Carnot's engine, working between steam point and ice point, will be :EasySingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.