Answer
$4.6V$
Work Step by Step
We can find the required emf as follows:
$\mathcal{E}=\frac{\rho dBL_s}{\mu_{\circ}r^2}$
We plug in the known values to obtain:
$\mathcal{E}=\frac{(2.3\times 10^{-8}\Omega.m)(0.045m)(0.015T)(1.65m)}{(4\pi \times 10^{-7}\frac{T.m}{A})(0.0021m)^2}$
$\mathcal{E}=4.6V$