Question

An oscillating electric dipole of moment \(\overrightarrow{d}(t) = d_0 \cos(\omega t) \hat{z}\) is placed at the origin as shown in the figure. Consider a point \(P(r, \theta, \phi)\) at a very large distance from the dipole. Here, \(r\), \(\theta\), and \(\phi\) are spherical polar coordinates. Which of the following statements is/are true for the intensity of radiation?

• A. Intensity is zero if P is on the z axis
• B. Intensity is zero if \( P \) is on the \( z \) axis.
• C. Intensity at \( P (r = R, \theta = \pi \, / \, 2, \phi = \pi \, / \, 4) \) is greater than that at \( P (r = R, \theta = \pi \, / \, 4, \phi = \pi \, / \, 4) \).
• D. Intensity at \( P (r = R, \theta = \pi \, / \, 2, \phi = \pi \, / \, 4) \) is equal to that at \( P (r = R, \theta = \pi \, / \, 4, \phi = \pi \, / \, 4) \).

Answer 1

The Correct Option is A, C

The correct Answers are (A):Intensity is zero if P is on the z axis ,(C):Intensity at \( P (r = R, \theta = \pi \, / \, 2, \phi = \pi \, / \, 4) \) is greater than that at \( P (r = R, \theta = \pi \, / \, 4, \phi = \pi \, / \, 4) \).