You have designed and constructed a solenoid to produce a magnetic field equal in magnitude to that of the earth (5.0 10-5 t). if your solenoid has 500 turns and is 29 cm long, determine the current you must use in order to obtain a magnetic field of the desired magnitude.

Carbon is allowed to diffuse through a steel plate 15 mm thick. the concentrations of carbon at the two faces are 0.65 and 0.30 kg c/m^3 fe, which are maintained constant. if the preexponential and activation energy are 6.2 x 10-7 m2 /s and 80,000 j/mol, respectively, compute the temperature at which the diffusion flux is 1.43 x 10^-9 kg/m^2 -s.