MCQ
The solid angle subtended by the total surface area of a sphere at the centre is:
- ✓$4\pi$
- B$2\pi$
- C$\pi$
- D$3\pi$
✓
Answer
Correct option: A.
$4\pi$
A steradian is the solid angle subtended at the center of a sphere of radius $r$ by a section of its surface area of magnitude equal to $r^2$. Since the surface area is $4 \pi r^2$, there are $4 \pi$ steradians surrounding a point in space.
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