Carbon is allowed to diffuse through a steel plate 9.7-mm thick. the concentrations of carbon at the two faces are 0.664 and 0.339 kg of carbon per m3 of iron, which are maintained constant. if the preexponential and activation energy are 6.5 x 10-7 m2/s and 82 kj/mol, respectively, calculate the temperature (in k) at which the diffusion flux is 3.2 x 10-9 kg/(m2-s).

844°C

Explanation:

The problem can be easily solve by using Fick's law and the Diffusivity or diffusion coefficient.

We know that Fick's law is given by,

Where is the concentration of gradient

D is the diffusivity coefficient

and J is the flux of atoms.

In the other hand we have, that

Where is the proportionality constant,

R is the gas constant, T the temperature and is the activation energy.

Replacing the value of diffusivity coefficient in Fick's law we have,

Rearrange the equation to get the value of temperature,

We have all the values in our equation.

Substituting,

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

the answer is b

explanation: