Physics Electrostatics MDCAT 2018
PMDC Verified Question 104 of 131
Q.97 Coulomb's law is given by the formula \( F=k \frac{q_1 q_2}{r^2} \). The magnitude of k having the unit of \( \text{Nm}^2\text{C}^{-2} \) for free space is equal to
A
\( 9 \times 10^7 \)
B
\( 6 \times 10^7 \)
C
\( 10 \times 10^9 \)
D
\( 9 \times 10^9 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( 9 \times 10^9 \)
1. Concept:

Coulomb's constant \( k \) characterizes the strength of the electrostatic force in a vacuum or free space.

2. Formula:

$$ k = \frac{1}{4 \pi \epsilon_0} $$

3. Solution:

  • Given the vacuum permittivity \( \epsilon_0 = 8.85 \times 10^{-12} \text{ C}^2/(\text{N m}^2) \).


  • Evaluating \( k = \frac{1}{4 \pi (8.85 \times 10^{-12})} \) yields approximately \( 8.99 \times 10^9 \), heavily standardized as \( 9 \times 10^9 \text{ Nm}^2\text{C}^{-2} \) for test purposes.


4. Why other options are incorrect:

They represent incorrect orders of magnitude and incorrect base digits. \( 9 \times 10^9 \) is a universally memorized physical constant.

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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