Physics Current Electricity ETEA 2023
PMDC Verified Question 39 of 112
Which of the following the copper conductor that has the least resistance must be?
A
Thick, short and cool
B
Thin, long and hot
C
Thick, long and hot
D
Thin, short and cool
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Thick, short and cool
Concept:

Resistance connects linearly with length, inversely with area, and linearly with temperature for metallic conductors.

Formula:

$$ R = \rho_0(1+\alpha \Delta T) \frac{L}{A} $$

Solution:

  • To get the least resistance, we must minimize the numerator and maximize the denominator.


  • Thick (large area \( A \)) minimizes resistance.


  • Short (small length \( L \)) minimizes resistance.


  • Cool (low temperature) minimizes resistivity \( \rho \).


  • Therefore, "Thick, short and cool" gives the absolute lowest possible resistance.


Why other options are incorrect:

  • Opt B: This combination yields the absolute highest resistance.


  • Opt C & D: Have conflicting features that don't yield the absolute minimum.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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