Working with thermionic emission to determine the current from a platinum wire.

Find the value of the thermionic current in Amp/cm² for a platinum filament whose work function is 4.1 eV and temperature is 2000 K. The emission constant A is 120 A/(cm² K²).

Young's modulus

Copper has a breaking stress of 3 x 10^8 N/m2. (a) What is the maximum load that can be hung from a copper wire of diameter of 0.42 mm before it breaks? (b) If half this maximum load is hung from the wire, by what percentage of its length will it stretch ?

quasi Fermi levels,conductivity

An undoped Si sample is optically excited at 300K such that Gop=10^19 ehp/cm^3s and taun=taup=1 microseconds. (a) What is the separation of the quasi Fermi levels (Efn-Efp)? (b) Where is Efn and Efp with respect to the intrinsic Fermi level Ei? (c) What is the change in conductivity due to excess carriers? What are the answers and how did you find them? Thank you. ---I double checked. There is no further information or parameters given with this problem. I'm stumped.

Designing a fun and happy resistor

An n-type Si resistor is to be designed so that it carries a current of 5mA with an applied voltage of 5V. T=300K. Mn*=.26M0. M0=9.11x10^31Kg. (a) If Nd=10^15/cm^3 and Na=0, design a resistor to meet the required specifications. (b) If Nd=3x10^16/cm^3 and Na=2.5x10^16/cm^3, redesign the resistor. What are the answers and how did you get them? I don't even know where to begin.

Finding Nc

Consider a gold Schottkey diode at T=300k formed on a n-type GaAs doped at Nd=5x10^16 cm^-3. Among other things find Phi|n. Phi|n=KT/e*ln(Nc/Nd) I don't understand how to get Nc from the information given here. What is NC given the information stated in the problem? Thanks.