A two-port network as illustrated in Figure 12.2 has the following parameters: $y_{11}=0$; $y_{12}=0 ; \quad y_{21}=3.5 \times 10^{-3} \mathrm{~S} ; y_{22}=1 \times 10^{-4} \mathrm{~S}$. If an external load resistance of $12 \mathrm{k} \Omega$ is connected to the output, what is the voltage gain of this network?