A point source of light is placed at the centre of curvature of a hemispherical surface. The radius of curvature is r and the inner surface is completely reflecting. Find the force on the hemisphere due to the light falling on its if the source emits a power W.

Explanation

To solve the problem of finding the force on a hemispherical surface due to light emitted from a point source at its center of curvature, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Setup**:
- We have a point source of light located at the center of curvature of a hemispherical surface. The radius of curvature is \( r \), and the inner surface of the hemisphere is completely reflecting.

2. **Power Emitted by the Source**:
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