1. Consider the circuit shown below. Find the equivalent Thevenin’s voltage between nodes A and B.
a) 8
b) 8.5
c) 9
d) 9.5
Explanation: The thevenin’s voltage is equal to the open circuit voltage across the terminals AB that is across 12Ω resistor. Vth = 10×12/14 = 8.57V.
2. Consider the circuit shown below. Find the thevenin’s resistance between terminals A and B.
a) 1
b) 2
c) 1.7
d) 2.7
Explanation: The resistance into the open circuit terminals is equal to the thevenin’s resistance => Rth = (12×2)/14 = 1.71Ω.
3. Consider the circuit shown below. Find the current flowing through 24Ω resistor.
a) 0.33
b) 0.66
c) 0
d) 0.99
Explanation: The equivalent thevenin’s model of the circuit shown is
I=8.57/(2.4+1.71)=0.33A.
4. Determine the equivalent thevenin’s voltage between terminals A and B in the circuit shown below.
a) 0.333
b) 3.33
c) 33.3
d) 333
Explanation: Let us find the voltage drop across terminals A and B. 50-25=10I+5I => I=1.67A. Voltage drop across 10Ω resistor = 10×1.67=16.7V. So, Vth=VAB=50-V=50-16.7=33.3V.
5. Find the equivalent thevenin’s resistance between terminals A and B in the circuit shown below.
a) 333
b) 33.3
c) 3.33
d) 0.333
Explanation: To find Rth, two voltage sources are removed and replaced with short circuit. The resistance at terminals AB then is the parallel combination of the 10Ω resistor and 5Ω resistor => Rth=(10×5)/15=3.33Ω
6. Determine the equivalent thevenin’s voltage between terminals A and B in the circuit shown below.
a) 5
b) 15
c) 25
d) 35
Explanation: Current through 3Ω resistor is 0A. The current through 6Ω resistor = (50-10)/(10+6)=2.5A. The voltage drop across 6Ω resistor = 25×6=15V. So the voltage across terminals A and B = 0+15+10 = 25V.
7. Find the equivalent thevenin’s resistance between terminals A and B in the following circuit.
a) 6
b) 6.25
c) 6.5
d) 6.75
Explanation: To find Rth, two voltage sources are removed and replaced with short circuit => Rth=(10×6)/(10+6)+3=6.75Ω.
8. Determine the equivalent thevenin’s voltage between terminals ‘a’ and ‘b’ in the circuit shown below.
a) 0.7
b) 1.7
c) 2.7
d) 3.7
Explanation: The voltage at terminal a is Va=(100×6)/16=37.5V, The voltage at terminal b is Vb=(100×8)/23=34.7V. So the voltage across the terminals ab is Vab=Va-Vb=37.5-34.7=2.7V.
9. Find the equivalent thevenin’s resistance between terminals A and B in the circuit shown below.
a) 6
b) 7
c) 8
d) 9
Explanation: To find Rth, two voltage sources are removed and replaced with short circuit => Rab=(6×10)/(6+10)+(8×15)/(8+15)=8.96≅9V.
10. Find the current through 5Ω resistor in the following circuit.
a) 0.1
b) 0.2
c) 0.3
d) 0.4
Explanation: The Equivalent Thevenin’s circuit for the circuit shown above is
I=2.7/(8.96+5)=0.193A≅0.2A.