Question

4.38 A diode operates in a series circuit with a resistance R and a dc source V. A designer, considering using a constant-voltage model, is uncertain whether to use 0.7 V or 0.6 V for VD. For what value of V is the difference in the calculated values of current only 1%? For V = 3 V and R = 1 k!, what two current estimates would result from the use of the two values of VD? What is their percentage difference?

Answer 1

a.
`V=9.4V`

b.
`i_(D1)=2.3x10^(-3)A`

`i_(D2)=2.4x10^(-3)A`

Step-by-step explanation:

Using law Ohm to find the current in the circuit with a diode and resistance R

`i_D=(V-V_D)/(R)`

a.

`i_(D2)=1.01*i_(D1)`

`(V-0.7)/(R)=1.01*(V-0.6)/(R)`

`(V-0.7)=1.01*(V-0.6)`

`V-0.7=1.01*V-0.606`

`V=(0.094)/(0.01)=9.4V`

b.

`i_(D1)=(V-V_D)/(R)`

`i_(D1)=(3V-0.7)/(1k)`

`i_(D1)=2.3x10^(-3)A`

`i_(D2)=(3V-0.6)/(1k)`

`i_(D2)=2.4x10^(-3)A`