A spherical steel ball of 12 mm diameter is initially at 1000 K. It is slowly cooled in a surrounding of 300 K. The heat transfer coefficient between the steel ball and the surrounding is 5 W /m2K. The thermal conductivity of steel is 20 W/mK. The temperature difference between the centre and the surface of the steel ball is

Large because conduction resistance is far higher than the convective resistance

Large because conduction resistance is far less than the convective resistance

Small because conduction resistance is far higher than the convective resistance

Small because conduction resistance is far less than the convective resistance

A spherical steel ball of 12 mm diameter is initially at 1000 K. It is

1.	A spherical steel ball of 12 mm diameter is initially at 1000 K. It is slowly cooled in a surrounding of 300 K. The heat transfer coefficient between the steel ball and the surrounding is 5 W /m2K. The thermal conductivity of steel is 20 W/mK. The temperature difference between the centre and the surface of the steel ball is
A.	Large because conduction resistance is far higher than the convective resistance
B.	Large because conduction resistance is far less than the convective resistance
C.	Small because conduction resistance is far higher than the convective resistance
D.	Small because conduction resistance is far less than the convective resistance
Answer» E.

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