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Question #42185
The Question
A horizontal cylindrical container of cross-sectional area has adiabatic walls and contains one mole of an ideal monatomic gas. A frictionless, adiabatic piston is pushed inwards at a constant speed . Integrated into the piston is a conducting rod of length and electrical resistance . The rod slides on two perfectly conducting, parallel rails that run along the inner length of the cylinder and are shorted at the closed end. A non-uniform magnetic field perpendicular to the plane of the rails exists in the region, given by , where is the distance from the closed end. The entire electrical resistance is exposed to the gas, so all Joule heating is transferred to the gas. If the initial volume and temperature of the gas are and , and the gas is compressed to a volume , find the final temperature of the gas. (Given: , where is the universal gas constant).
Options
- A.
- B.
- C.
- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Intuition_Breaker
Train your brain to resist "obvious" answers that are designed to deceive your intuition.
Concepts Behind This Question
First Law Application|Motional EMF for Arbitrary Shapes|Integration
Why This Question Is Tricky
Common Mistakes
This problem couples the First Law of Thermodynamics with electromagnetic induction.
The primary trap is ignoring the Joule heating entirely, leading to the standard adiabatic result of 4T_0.
A secondary, highly lethal trap tests the calculation of magnetic flux in a non-uniform field: students who incorrectly assume flux is B(x) multiplied by Area (instead of integrating B dA) will obtain an EMF that is off by a factor of 2, leading to the incorrect option 19/4 T_0.
The problem rigorously tests the differential formulation of the First Law where mechanical work and internal heat generation occur simultaneously.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Thermodynamics - Class 11 Part 2 |
| Concept | First Law Application |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |