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Question #77831
The Question
A non-uniform electric field is given by , where is an unknown constant and is a known exact constant. A student determines by measuring the electric flux through an open surface bounded by the curve in the -plane. The true surface is a paraboloid defined by for . The student measures the base radius as with a relative error , and the flux with a relative error . However, the student incorrectly assumes the surface is a standard hemisphere of radius (). Let be the true maximum relative error in (derived from the correct surface geometry), and be the maximum relative error calculated by the student using their flawed geometric assumption. What is the magnitude of the difference ? (Assume the normal to the surface has a positive z-component).
Options
- A.
- B.
- C.
- D.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Multi-Concept_Bridge
Master problems that require linking physics and math concepts to solve complex competitive questions.
Concepts Behind This Question
Flux and Surface Geometry|Relative Error Propagation in Powers
Why This Question Is Tricky
Examiner Levers
Negative Thinking
Uses "NOT", "EXCEPT", or "INCORRECT" to flip the logic gate.
Difficulty Boost : +2Visualization Stress
Requires mental rotation or 3D mapping (Optics/Geometry/Vectors).
Difficulty Boost : +4Common Mistakes
This question tests the rigorous application of error propagation derived from first-principles vector calculus, weaponizing the definition of electric flux.
Students typically memorize the relative error formula for flux as , assuming a standard uniform field and spherical surface.
By introducing a non-spherical, variable-curvature surface (paraboloid) and a field with a spatial gradient (), the effective area becomes a complex polynomial function of the coordinates.
The lethal collision occurs when the student ignores that the 'power' of the radius in the error formula changes based on the flux penetration angle and the specific geometry of the surface.
The error propagates non-linearly through the spatial dependency of the flux, rendering the standard Power Law rule mathematically insufficient and exposing the flaw in assuming a generic hemispherical geometry.
Quick Facts About This Question
Question Information
| Subject | Physics |
| Chapter | Units and Measurements - Class 11 Part 1 |
| Concept | Relative Error Propagation in Powers |
| Difficulty | 8 |
| Cognitive Load | 8 |
| Target Solve Time | 180 sec |
| Access | Free |