Question 10.5: Analysis by Assumed Diode States Use the ideal-diode model t...

With D₁ off and D₂ on, the equivalent circuit is shown in Figure 10.16(b). Solving results in i_D2 = 0.5 mA. Since the current in D₂ is positive, our assumption that D₂ is on seems to be correct. However, continuing the solution of the circuit of Figure 10.16(b), we find that v_D1 = +7 V. This is not consistent with the assumption that D₁ is off. Therefore, we must try another assumption.
This time, we assume that D₁ is on and D₂ is off. The equivalent circuit for these assumptions is shown in Figure 10.16(c). We can solve this circuit to find that i_D1 = 1 mA and v_D2 = -3 V. These values are consistent with the assumptions about the diodes (D₁ on and D₂ off) and, therefore, are correct.