Discussion
Among electric field (\(\vec{E}\)), magnetic field (\(\vec{B}\)), angular momentum (\(\vec{L}\)), and vector potential (\(\vec{A}\)), which is/are odd under parity (space inversion) operation?
Answer: B
Under parity, \(\vec{E}\) and \(\vec{A}\) only are odd.
Parity sends \(\vec{r} \to -\vec{r}\). Polar (true) vectors change sign, while axial (pseudo) vectors, built as cross products of two polar vectors, do not.
- \(\vec{E}\) is polar: it is the force per unit charge, and force reverses with \(\vec{r}\). Odd.
- \(\vec{A}\) is polar: \(\vec{E} = -\nabla\phi - \partial\vec{A}/\partial t\), and \(\vec{E}\) is odd while \(\phi\) is a scalar, so \(\vec{A}\) must be odd too.
- \(\vec{L} = \vec{r} \times \vec{p}\) is axial: both factors reverse, so \(\vec{L}\) does not. Even.
- \(\vec{B} = \nabla \times \vec{A}\) is axial for the same reason. Even.
So options including \(\vec{B}\) or \(\vec{L}\), or leaving out \(\vec{A}\), are wrong.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development