Problem
Sample Problem
Find V1, V2, V3, VT, I1, I3, IT, RT
| I1 = I2 = I3 = IT = 2 A | RT = 1 + 4 + 5 = 10 Ω |
| V1 = I1R1 = 2(1) = 2 V | V2 = I2R2 = 2(4) = 8 V |
| V3 = I3R3 = 2(5) = 10 V | VT = ITRT = 2(10) = 20 V (Or VT = 2 + 8 + 10 = 20 V) |
Power = P = the rate at which work is done.
(units = Watts = W)
P = V I (always) PT = P1 + P2 + P3 + ……(always)
P1 = V1I1 = 2(2) = 4 W P2 = V2I2 = 8(2) = 16 W
P3 = V3I3 = 10(2) = 20 W PT = VTIT = 20(2) = 40 W
(Or PT = P1 + P2 + P3 = 4 + 16 + 20 = 40 W)
Practice Problem
Find V1, V2, V3, RT, I1, I2, I3, IT, P1, P2, P3, PT
RT = 6 + 8 + 10 = 24 Ω
IT = VT/RT = 72/24 = 3 A = I1 = I2 = I3
| V1 = I1R1 = 3(6) = 18 V | V2 = I2R2 = 3(8) = 24 V |
| V3 = I3R3 = 3(10) = 30 V | P1 = V1I1 = 18(3) = 54 W |
| P2 = V2I2 = 24(3) = 72 W | P3 = V3I3 = 30(3) = 90 W |
PT = VTIT = 72(3) = 216 W
(Or PT = P1 + P2 + P3 = 54 + 72 + 90 = 216 W)