Hi, could anyone explain the formula used (eg V,I,R,) for the following questions, you don't have to answere them just explain the working...thanks.

a) What is the reluctance of magnetic material 0.8m length, 0.6m^2 CSA, if the absolute permeability is (wierd u shape) U = 300 x 10^-7 web/at.

b) how to calculate magneto motive force? (not related to (a) )

Any feedback's great, thanks.