A pin fin of uniform, cross-sectional area is fabricated of an aluminum alloy (k= 160 w/m·k). the fin diameter is d= 4.2 mm, and the fin is exposed to convective conditions characterized by h= 231 w/m2·k. it is reported that the fin efficiency is ηf= 0.65. determine (a) the fin length l and the fin effectiveness ɛf. account for tip convection.

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation: