Physics Electromagnetism SZABMU 2024
PMDC Verified Question 1 of 58
A what value of angle between the magnetic field intensity and vector area, the magnetic flux becomes zero?
A
\( 0^\circ \)
B
\( 30^\circ \)
C
\( 45^\circ \)
D
\( 90^\circ \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: \( 90^\circ \)
Concept:

Magnetic flux is a dot product. It drops to zero when the two vectors are perfectly orthogonal (perpendicular) to each other.

Formula:

$$ \Phi = BA \cos(\theta) $$

Solution:

  • We need to find the angle \( \theta \) that makes \( \cos(\theta) = 0 \).


  • From basic trigonometry, the cosine function hits zero at \( 90^\circ \) (and \( 270^\circ \)).


  • At \( 90^\circ \), the magnetic field is grazing parallel to the actual surface plane, so exactly zero field lines "pierce" through the area.


Why other options are incorrect:

Option A (\( 0^\circ \)) maximizes the flux. Options B and C result in a fraction of the maximum flux (\( 0.866 \) and \( 0.707 \) respectively).

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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