Question

2. For the circuit in Figure 2, use the costan a. (12 pts) Determine the states (om or oft) of DI and D Tsw Dl is b. (6 pts) Determine the voltage Vi VI- (6 pts) Determine the voltage V2 c. 3. (7 pts) A diode has a de bias current of 6 mA. Determine its ac resistance, ra

Answer 1

Answer :- 2) The voltage sources are 5V and 1V(assuming, since picture is not clear). Let's assume current i₁ is flowing in left loop containg diode D1, in clockwise direction and current i₂ is flowing in right loop in anti-clockwise direction.

For loop1, we can write-
5 - 1000*i₁ - 0.7 = 0 => i₁ = 4.3 mA.

For loop2, we can write-
1 - 2000i₂ - 1.4 = 0 => i₂ = -0.2 mA.

So in loop2 current is flowing clockwise only. Hence our assumption was wrong.
Thus diode D1 is ON since forward biased, and diode D2 is off since reverse biased.

Voltage V1 is 0.7 V i.e. voltage accross the diode D1. Voltage V2 = 1V since diode D2 is off hence no current flow in second loop. Reverse biased diode is like open circuited.

Answer :- 3) The dynamic or ac resistanve is calculated by using the equation-

$r_{d}=\frac{0.026}{I_{DC}}$

Thus, r_d = 0.026 / 0.006 ohm = 4.33 ohm.