Devry Ect-122 Week 4 Assignment

Week 4 Assignment

11. Determine the potentiometer setting needed to set the current in Figure 4.33a to 18 mA.

You will have to set the potentiometer at 86 Ω.

R_T= V_T/I_T =(10 V)/(18 mA)=556 Ω

556 Ω-470 Ω=86 Ω

Figure 4.33

12. Determine the potentiometer setting needed to set the current in Figure 4.33b to 27 mA.

(University, 11/2012, p. 117)

You will have to set the potentiometer at 361 Ω.

R_T= V_S/I_T =(30 V)/(27 mA)=1111 Ω

1111 Ω-750 Ω=361 Ω

1. The table below refers to Figure 5.27. For each combination of branch currents, find the total circuit current.

Figure 5.27

I1 I2 I3 It

a. 12 mA 2.8 mA 6.6 mA _21.4 mA_

b. 5.5 mA 360 µA 1.04 mA _6.9 mA_

c. 43 mA 25 mA 3.3 mA _71.3 mA_

d. 500 µA 226 µA 1.08 mA _1.806 mA_

(University, 11/2012, p. 141)

3. Determine the values of the branch currents and the total current for the circuit shown in Figure 5.28a.

The current for the 1 kΩ resistor is 8 mA and the current for the 200 Ω resistor is 40 mA. Therefore, the total current would be 48 mA.

I_1=V/R=(8 V)/(1 kΩ)=8 x 〖10〗^(-3) A=8 mA

I_2=V/R=(8 V)/(200 Ω)=40 x 〖10〗^(-3) A=40 mA

I_T= I_1+I_2=8 mA+40 mA=48 mA

Figure 5.28

(University, 11/2012, pp. 141)

6. Determine the values of the branch currents and the total current for the circuit shown in Figure 5.29b.

The current for the 220 Ω resistor is 68 mA, the current for the 100 Ω resistor is 150 mA, and the current for the 470 Ω resistor is 32 mA. Therefore, the total current would be 250 mA.

I_1=V/R=(15 V)/(200 Ω)=68 x 〖10〗^(-3) A=68 mA

I_2=V/R=(15 V)/(100 Ω)=150 x 〖10〗^(-3) A=150 mA

I_3=V/R=(15 V)/(470 Ω)=32 x 〖10〗^(-3) A=32 mA

I_T= I_1+I_2+I_3=68 mA+150 mA+32 mA=250 mA

Figure 5.29

(University, 11/2012, p. 142)

Figure 5.29

10. Calculate the value of RT for the circuit shown in Figure 5.29b.

The total resistance is 60.24 Ω

R_T=1/(1/R_1 +1/R_2 +⋯+〖1/R〗_N ) =1/(1/〖220 〗_1 +1/〖100 〗_2 +〖1/470〗_3 )=1/(.0045 +.01 +.0021 ) =1/(.0166...