Activity 1.1.5a Circuit Theory: Hand Calculations
Introduction
In this activity you will gain experience applying Ohm’s Law and Kirchhoff’s Voltage and
Current Laws to solve simple series and parallel circuits.
Equipment
•
Calculator
Procedure
1. For each of the resistors shown below, use Ohm’s Law to calculate the unknown
quantity. Be sure to put your answer in proper engineering notation and use the
correct units.
3.5/470= 7.43 mA
3.5/ 15.5 ua = 225.806kΩ
1.4 mA *22kOhms = 30.8kV
2.4 mV/ 10uA = 240Ω
20V/ 6.8 k ohms = 2.94mV
2.5 A/120 ohms = 300V
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Digital Electronics Activity 1.1.5a Circuit Theory: Hand Calculations – Page 1
2. For each of the circuits shown below, calculate the value for RT.
Be sure to put your answer in proper engineering notation and use the correct units.
Calculations:
a)
820 + 1200 + 150 = 2.17k ohms
a)
b)
470 + 3900 + 4700 + 1800 = 10.9k ohms
b)
c)
1/(1/5600+1/680+1/8200) = 564.49 ohms
c)
d)
1/(2/600+2/300+ 1/200) = 66.7 ohms
d)
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Digital Electronics Activity 1.1.5a Circuit Theory: Hand Calculations – Page 2
3. Using the laws of circuit theory, solve for RT, IT, VR1, VR2, VR3, & VR4. Be sure to put
your answer in proper engineering notation and use the correct units.
Using the calculations from problem (3), verify your results using Kirchhoff’s Voltage Law.
2700+10000+3300+8200= 2.42 k ohms
6/2420 = 2.48 uA
VR1 = 2700*2.48uA=669.6 uV
VR2 = 10000*2.48uA = 2.48mV
VR3 = 3300*2.48uA = 818.4uV
VR4 = 8200*2.48uA=2.034mV
RT*IT=VT
0.00248*2420=1.0016
4. Using the laws of circuit theory, solve for RT, IT, IR1, IR2, & IR3. Be sure to put your
answer in proper engineering notation and use the correct units.
Using the calculations from problem (4), verify your results using Kirchhoff’s Current Law.
1/(1/8200+1/6800+1/4700) =2.08 k ohms
IR1=12/8200=1.46mA
IR2=12/6800=1.77mA
IR3=12/4700=2.55mA
IT = 5.78mA
© 2014 Project Lead The Way, Inc.
Digital Electronics Activity 1.1.5a Circuit Theory: Hand Calculations – Page 3