The emissivity of tungsten is aproximately 0.35. A tungsten sphere 1 cm in radius is suspended within a large evacuated enclosure whose walls are at 300 K. What power input is required to maintain the sphere at a temperature of 3000 K if heat conduction along the support is neglected?`sigma=5.67xx10^-8` SI units.

Explanation

To solve the problem, we need to determine the power input required to maintain a tungsten sphere at a temperature of 3000 K while it is suspended in an enclosure at 300 K. The power input is determined by the radiation heat transfer from the sphere to the walls of the enclosure.

### Step-by-Step Solution:

1. **Identify Given Values:**
- Emissivity of tungsten, \( \epsilon = 0.35 \)
- Radius of the sphere, \( R = 1 \, \text{cm} = 0.01 \, \text{m} \)
- Temperature of the sphere, \( T_1 = 3000 \, \text{K} \)
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