Based on the cause-and-effect relationship between the magnets, which phenomenon is the teacher modeling for her student?

Anybody wanna ? (picture included? )

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.

What are the similarities & differences between a thermistor and a light dependent resistor in physics?