Q 12-01-025JEE MainJEE Main 2026 (4 Apr, Shift 2)Hard
A rigid dipole undergoes a simple harmonic motion about its centre in the presence of an electric field $\vec{E}_1 = E_0\hat{x}$. If another electric field $\vec{E}_2 = 2E_0(\hat{y} + \hat{z})$ is introduced to the system, what will be the percentage change in the frequency of the oscillation (approximate)?
Answer: (A) $73\%$
For small oscillations about the field direction, $\tau = -pE\theta$, so $\omega = \sqrt{\dfrac{pE}{I}} \propto \sqrt{E}$.
New field: $\vec{E} = E_0\hat{x} + 2E_0\hat{y} + 2E_0\hat{z}$, with magnitude $E_0\sqrt{1 + 4 + 4} = 3E_0$.
$\dfrac{f'}{f} = \sqrt{3} \approx 1.73$, an increase of about $73\%$.
Solution by Sreeraj P, M.Sc Physics