8 simple circuits
- 1. Simple Circuits Equivalent resistance If you replaced all the resistors in the circuit with one resistor, then how many ohms would it have?
- 2. Simple Series 9 V R1 = 5 Ω R2 = 7 Ω V = 9 V Rs = 5 + 7 = 12 Ω I = 0.75 A V = I R 9 = I (12) I = 0.75 A I = 0.75 A I = 0.75 A V = 3.75 V V = 5.25 V • Resistors in series add up. • Find the total current. (V= IR) • In a series circuit, the currents are constant. • Find the voltages. (V=IR) • Double check yourself In series, the voltages add up. 3.75 + 5.25 9
- 3. Simple Parallel 9 V R1 = 4 Ω R2 = 12 Ω V = 9 V 1/Rp = 1/4 + 1/12 Rp = 3 Ω I = 3 A V = I R 9 = I (3) I = 3 A I = 2.25 A I = 0.75 A V = 9 V V = 9 V • Resistors in parallel are 1/R = 1/R + 1/R. • Find the total current. (V= IR) • In a parellel circuit, the voltages are constant. • Find the currents. (V=IR) • Double check yourself In parallel circuit, the currents add up. 2.25 + 0.75 3
- 4. 12 V 12 V R = 4 Ω R = 5 Ω R = 6 Ω 1/Rp = 1/5 + 1/6 Rp = 2.73 ΩR = 4 Ω Rs = 4 + 2.73 = 6.73 Ω 12 V I = 1.78 A I = 1.78 A I = 1.78 A V = 7.12 V V = 4.86 V V = 4.86 V V = 4.86 V I = 0.81 A I = 0.96 A 7.12 +4.86 12 Current is equal in series. 0.96 +0.81 1.78 Voltages are equal in parallel. Voltages add up. Currents add up. Combine these two first into 1 resistor!
- 5. R1 = 2 Ω R2 = 4 Ω I = 1.76 A I = 1.76 A V = 2.11 V V = 3.85 V V = 6 V Rs = 1.2 + 2.2 = 3.4 Ω I = 1.76 A 1/Rp = 1/2 + 1/3 Rp = 1.2 Ω R2 = 5 ΩR2 = 3 Ω 1/Rp = 1/4 + 1/5 Rp = 2.2 Ω V = 6 V V = 6 V V = 2.11 V V = 3.85 V I = 0.77 A I = 1.06 A V = 3.85 V I = 0.96 A V = 2.11 V I = 0.70 A
- 6. 120 V 120 V 72 Ω 120 V I = 1.78 A I = 1.6 A I = 1.6 A V = 115 V V = 4.32 V 4 Ω 27 Ω 3 Ω 72 Ω 4 Ω 1/Rp = 1/27 + 1/3 Rp = 2.7 Ω 4 Ω Rs = 72 + 2.7 = 74.7 Ω 1/Rp = 1/74.7 + 1/4 Rp = 3.8 Ω V = 120 V V = 120 V I = 1.6 A I = 30 A V = 120 V V = 120 V I = 1.6 A I = 30 A
- 7. 120 V 120 V 72 Ω 120 V I = 1.78 A I = 1.6 A I = 1.6 A V = 115 V V = 4.32 V 4 Ω 27 Ω 3 Ω 72 Ω 4 Ω 1/Rp = 1/27 + 1/3 Rp = 2.7 Ω 4 Ω Rs = 72 + 2.7 = 74.7 Ω 1/Rp = 1/74.7 + 1/4 Rp = 3.8 Ω V = 120 V V = 120 V I = 1.6 A I = 30 A V = 120 V V = 120 V I = 1.6 A I = 30 A