A diagram of an n-type material of resistance 2 kilo-newton connected across a 15DC supply. Taking charge e=1.6×10^-19 coloumbs . Determine the current through the material.

Apreheater involves the use of condensing steam at 100°c on the inside of a bank of tubes to heat air that enters at 1 atm and 25°c. the air moves at 5 m/s in cross flow over the tubes. each tube is 1 m long and has an outside diameter of 10 mm. what is the minimum value of nl needed to achieve an outlet temperature of t 75 c? what is the corresponding pressure drop across the tube bank?