Question

Under parity and time reversal transformations, which of the following statements is(are) TRUE about the electric dipole moment $\vec{p}$ and the magnetic dipole moment $\mu$?

• A. $\vec{p}$ is odd under parity and $\mu$ is odd under time reversal
• B. $\vec{p}$ is odd under parity and $\mu$ is even under time reversal
• C. $\vec{p}$ is even under parity and $\mu$ is odd under time reversal
• D. $\vec{p}$ is even under parity and $\mu$ is even under time reversal

Hint:

For electromagnetic moments, remember that $\vec{p}$ is odd under parity and $\mu$ is odd under time reversal.

Answer 1

The Correct Option is A

- The electric dipole moment $\vec{p}$ changes sign under parity transformation. That is, under parity, $\vec{p}$ transforms as $\vec{p} ⇒ -\vec{p}$, so it is odd under parity.
- The magnetic dipole moment $\mu$ changes sign under time reversal transformation. Specifically, under time reversal, $\mu ⇒ -\mu$, so it is odd under time reversal.
Thus, the correct answer is (A).