2011-07-01 Finding the potential and current in a circuit with one Si diode

Use KVL and KCL to find the potential V_C and the current flowing through Si diode.

Solution

Since the potential +5 V is higher than 0V, the Si diode tends to be forward biased.

KVL;

0 V+ 0.7 V = V_C

V_C = 0.7 V Ans

KVL;

0 V + (4 kΩ)(I_4kΩ) = V_C = 0.7 V

I_4kΩ = 0.7 V / 4 kΩ = 0.18 mA

KVL;

V_C + (2 kΩ)(I_2kΩ) = 5 V

I_2kΩ = (5 V - 0.7 V) / 2 kΩ = 2.15 mA

KCL;

I_Si + I_4kΩ = I_2kΩ

I_Si = 2.15 mA - 0.18 mA = 1.97 mA Ans