The xurcurrent in the coil increases uniformly from $0\mathrm{.}4$s to $1$A in $2$s$,$so that the voltage across the coil is $60$mV$.$Calculate the inductance of the coil.Given: V$=60$mV$,$ t$2=0\mathrm{.}4$s$,$t$1=2$s$,$I$=1$A