A point light source emits E.M. waves in free space. A detector… | JEE Main 2026 (6 Apr, Shift 1)

Q1JEE Main 2026 · 6 APR · SHIFT 1Easy

Energy Density & Intensity

A point light source emits E.M. waves in free space. A detector, placed at a distance of $L\text{ m}$ , measures the intensity as $I_o$ . The detector is now shifted to another location on the same spherical surface ensuring the angle between original location and new location as $45^\circ$ . The measured intensity at new location will be ______.

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Answer: (b)

A point source radiates equally in all directions: $I = \dfrac{P}{4\pi L^2}$ .
Every point on the same sphere is at the same distance $L$ , so $I$ is the same.
So the answer is (b) $I_o$ .

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