Physics - Heat & Thermo Question with Solution | TestHub

PhysicsHeat & ThermoSecond Law of ThermodynamicsHard2 minPYQ_2015
PhysicsHardsingle choice

A solid body of constant heat capacity1 J -1is being heated by keeping it in contact with reservoirs in two ways: (i) Sequentially keeping in contact with 2 reservoirs such that each reservoir supplies the same amount of heat. (ii) Sequentially keeping in contact with8reservoirs such that each reservoir supplies the same amount of heat. In both, cases the body is brought from initial temperature100 Kto final temperature200 K. Entropy change of the body in the two cases respectively is: Note: This question was awarded as a bonus since temperatures were given in centigrade instead of in Kelvin. Proper corrections are made in the question to avoid it.

Options:

Answer:
C
Solution:

Change in entropy, 

dS=dQTΔQ=heatsupplied=CΔT{C=J °C-1}dQ=CdtdS=CdTTIntergratingbothsidesSiSfdS=CdTTSfSi=ΔS=C.lnT|100200ΔS=C[ln200ln100]=Cln2andC=J °C-1ΔS=ln2Entrpoy change in same for both cases as C is constant, andtemperature change (i.e. from 100 to 200) is same.

Stream:JEESubject:PhysicsTopic:Heat & ThermoSubtopic:Second Law of Thermodynamics
2mℹ️ Source: PYQ_2015

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