Physics Current Electricity UHS 2023
PMDC Verified Question 25 of 112
The following formula can be used to determine the resistance of a length of conductor. \( R = \rho l/A \). In the formula, the symbol \( \rho \) stands for the:
A
Cross-sectional area of the conductor in \( \text{m}^2 \)
B
Product of the length of the conductor in metes
C
Resistivity of the material in units of ohm-meters
D
Resistance of the conductor in units of ohms per meter
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Resistivity of the material in units of ohm-meters
Concept:

The formula connects bulk resistance to intrinsic material properties.

Solution:

  • In the equation \( R = \rho \frac{l}{A} \), \( R \) is resistance, \( l \) is length, and \( A \) is the cross-sectional area.


  • The symbol \( \rho \) (rho) represents the constant of proportionality known as Resistivity (or specific resistance).


  • Its SI unit is Ohm-meters (\(\Omega \cdot \text{m}\)).


Why other options are incorrect:

  • Opt A: Area is represented by \( A \).


  • Opt D: Resistance per meter is \( R/l \), not \( \rho \).

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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