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Solving Series circuits How to Whiteboards. A Series Circuit has many voltages, but only one current. A 1. Note that the total voltage drops add to source voltage. 1 . V 1 = IR = (3 A)(1 ) = 3 V. V 1. 24 V. V 2 = IR = (3 A)(2 ) = 6 V. 2 . V 2. A 2.
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Solving Series circuits • How to • Whiteboards
A Series Circuit has many voltages, but only one current A1 Note that the total voltage drops add to source voltage 1 V1 = IR = (3 A)(1 ) = 3 V V1 24 V V2 = IR = (3 A)(2 ) = 6 V 2 V2 A2 V3 = IR = (3 A)(5 ) = 15 V 5 V3 A3 • How to solve series: • 1. Find the total resistance (1 + 2 + 5 = 8) • 2. Find the one current (I = V/R = (24 V)/(8 ) = 3 A - all • the ammeters read 3 A) • 3. Use V = IR to find voltages (voltage drops)
I A1 A2 R1 R2 R3 • Analogy - ping pong balls - electrons • All start moving at once/speed of impulse, speed of particles • Resistance anywhere along the tube limits flow everywhere
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What is the Total resistance? 11 7 5 20.0 V R tot = R1 + R2 + R3 ... = 5 + 7 + 11 = 23 23
What is the reading on both ammeters? (The one current) (answer with 3 SF) 11 5 7 A2 A1 20 V I = V/R = (20 V)/(23 ) = .8696 = .870 A .870 A
What do the voltmeters read? (3 SF) V1 V2 11 7 5 20.0 V V = IR V1 = (5 )(.8696 A) = 4.35 V V2 = (18 )(.8696 A) = 15.7 V 4.35 V, 15.7 V
What do the voltmeters read? (3 SF) V1 V2 11 9 5 35 V 13 3 R = 41 , I = .8537 A V = IR V1 = (5 )(.8537 A) = 4.27 V V2 = (20 )(.8537 A) = 17.1 V V3 = (13 )(.8537 A) = 11.1 V V3 4.27 V, 17.1 V, 11.1 V
What do the voltmeters read? (3 SF) V1 V2 200 90 500 V3 110 120 V 130 R = 1030 , I = .1165 A V = IR V1 = (500 )(.1165 A) = 58.3 V V2 = (90 )(.1165 A) = 10.5 V V3 = (330 )(.1165 A) = 38.4 V 58.3 V, 10.5 V, 38.4 V
What is the value of the mystery resistor if V1 reads 3.17 V (3 SF) V1 ??? 7 5 20 V I = V/R = (3.17 V)/(5 )= .634 A Rtot = V/I = (20 V)/(.634 A) = 31.55 Rtot = 5 + 7 + ?? = 31.55 ?? = 19.5 19.5
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