AIIMS 2019 Physics Electron Motion Assertion Reason Question
Assertion: For revolving electron, direction of angular momentum and magnetic moment are opposite.
Reason: Charge of electron is negative.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Correct Answer
Detailed Explanation
Option A is correct because the assertion states that the angular momentum (L) and magnetic moment (μ) of a revolving electron are opposite due to the electron's negative charge. This is true, as the angular momentum vector points in the direction of rotation (using the right-hand rule), while the magnetic moment, which is proportional to the angular momentum but directed opposite for a negative charge, points in the opposite direction.
Other options are incorrect because options B and C suggest that either the reason does not explain the assertion or that the assertion is false, which is not the case; both are true. Option D incorrectly claims that the assertion is false while the reason is true, which contradicts the established relationship between angular momentum and magnetic moment for negatively charged particles.
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