Step 1: Understanding the Concept:
For a uniform point source of light, the intensity radiates equally in all directions (isotropically). It only depends on the radial distance from the source following the inverse-square law.
Step 2: Key Formula or Approach:
The intensity \(I\) at a distance \(R\) from a source of power \(P\) is:
\[ I = \frac{P}{4\pi R^2} \]
Step 3: Detailed Explanation:
The light source is located perfectly at the center of the sphere. Both points A and B lie on the surface of the sphere.
Because they are on the surface, the radial distance from the center to point A is \(R\), and the radial distance to point B is also \(R\).
Since the intensity strictly depends on the distance \(R\) and not the angular position:
\[ I_A = \frac{P}{4\pi R^2} = I \]
\[ I_B = \frac{P}{4\pi R^2} = I \]
Therefore, the intensity at B is exactly the same as at A.
Step 4: Final Answer:
The intensity at point B is \(I\).
