[UPSC CSE 2008] Semiconductors/Solar cell (Q240, 20M)

Explain the switching action of a FET. Two JFETs are connected in parallel with $\gamma_{d1}$ (drain resistance) $= 20\text{ k}\Omega$ , $\gamma_{d2} = 30\text{ k}\Omega$ and $g_{m1}$ (transconductance) $= 2\text{ m-mho}$ and $g_{m2} = 4\text{ m-mho}$ . Find the efffective $\gamma_d$ and $g_m$ .