A $15-$cm$-$diameter, $1\mathrm{.}0-$m$-$long solenoid is wound with $2000$ turns of superconducting wire. When the magnet is turned on$,$ the current increases from $0$ to $I_{\text{m}\text{a}\text{x}}$ in $2\mathrm{.}5$ s $.$ At $t=1\mathrm{.}0s,$ the induced electric

What is the solenoid's steady magnetic field strength? field midway between the axis and the windings is $7\mathrm{.}5{10}^{-3}\frac{V}{m}.$

Express your answer with the appropriate units.