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For a current carrying wire of 20 mm diameter exposed to air (h = 20 W/m²K), maximum heat dissipation occurs when thickness of insulation (0.5 W/mK) is
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- 30 mm
- 25 mm
- 20 mm
- 15 mm
Correct Option: D
For maximum heat dissipation,
Critical radius,
| rc = | ||
| h |
| where k = 0.5 | ||
| mK |
| h = 20 | , r = 10 mm | |
| m²K |
| rc = | ||
| 20 |
= 25 mm
Insulation thickness = rc – r
= 25 – 10
= 15 mm
