Answer:
b). The same for all pipes independent of the diameter
Explanation:
We know,
From the above formulas we can conclude that the thermal resistance of a substance mainly depends upon heat transfer coefficient,whereas radius has negligible effects on heat transfer coefficient.
We also know,
Factors on which thermal resistance of insulation depends are :
1. Thickness of the insulation
2. Thermal conductivity of the insulating material.
Therefore from above observation we can conclude that the thermal resistance of the insulation is same for all pipes independent of diameter.