Archive 2010
Tech Talk
By Jim Purvis WA7HRG
In lasts months column I presented some explanation of Ohms Law and how it related to Voltages, Current and Power in a circuit. Along with that was a simple resister network and a challenge to calculate the voltage, current, and power for each component. And as promised, here are the answers.
Answers to the Ohms Law Challenge
1
Total Equivalent Resistance = R1+ 1 + 1
R2 R3+R4
=1K + 1
.0002+.0005
=1K+1428.5
=2,428.5 ohms
Total Current (I) = E E=13.5-Drop across D1
Rt
= 12.8
2428.5
= .0052 A
Total Power Dissipated = IxE
= .0052x12.8
= .0665 Watts
Total current through D1 = Total ckt current
= .0052 A
Power Dissipated by D1 = IxE
= .0052x.7
= .00364 Watts
VR1 = IxR IR1 = Total I PR1 = IxE
= .0052x1K = .0052A = .0052x5.2
= 5.2V = .02704 Watts
VR2 = (13.5-V-drop D1)-VR1 IR2 = E/R PR2 = IxE
= (13.5-.7)-5.2 = 7.6/5K = .00125x7.6
= 7.6 V = .00152 A = .001155 Watts
VR3,R4 = Vr2/2 IR3,R4 = E/R PR3,R4 = IxE
= 7.6/2 = 3.8/1K =.0038x3.8
= 3.8 V = .0038 A = .01444 Watts
Tech Talk
By Jim Purvis WA7HRG
In lasts months column I presented some explanation of Ohms Law and how it related to Voltages, Current and Power in a circuit. Along with that was a simple resister network and a challenge to calculate the voltage, current, and power for each component. And as promised, here are the answers.
Answers to the Ohms Law Challenge
1
Total Equivalent Resistance = R1+ 1 + 1
R2 R3+R4
=1K + 1
.0002+.0005
=1K+1428.5
=2,428.5 ohms
Total Current (I) = E E=13.5-Drop across D1
Rt
= 12.8
2428.5
= .0052 A
Total Power Dissipated = IxE
= .0052x12.8
= .0665 Watts
Total current through D1 = Total ckt current
= .0052 A
Power Dissipated by D1 = IxE
= .0052x.7
= .00364 Watts
VR1 = IxR IR1 = Total I PR1 = IxE
= .0052x1K = .0052A = .0052x5.2
= 5.2V = .02704 Watts
VR2 = (13.5-V-drop D1)-VR1 IR2 = E/R PR2 = IxE
= (13.5-.7)-5.2 = 7.6/5K = .00125x7.6
= 7.6 V = .00152 A = .001155 Watts
VR3,R4 = Vr2/2 IR3,R4 = E/R PR3,R4 = IxE
= 7.6/2 = 3.8/1K =.0038x3.8
= 3.8 V = .0038 A = .01444 Watts