An inductor has N $=850$ turns. When the current going through it is I $=0\mathrm{.}52$ A$,$ the magnetic flux through one coil is $=3\mathrm{.}210-6$ T$$m$2.$ The current is then changed to I$1=1\mathrm{.}76$ A in $$t $=4\mathrm{.}5$ s$.$

Express the inductance L in terms of N$,$ I and $.$

Calculate the numerical value of L in H$.$

Express the magnitude of the induced emf in terms of L$,$ I, I$1,$ and $$t$.$

Calculate the numerical value of in V$.$