A pin fin of uniform cross-sectional area is fabricated of an aluminum alloy (k = 160W m^-1 K^-1 ). The fin diameter is D = 4 mm, and the fin is exposed to convective conditions characterized by h = 220W m^-2 K^-1 . It is reported that the fin efficiency is ?f = 0.65. Account for convection heat transfer at the fin tip.

Questions: 

(a) What is the length of the fin, L?

(b) What is the fin effectiveness ?