Announcement Next Exam will be on the Thursday when we get back from break The EM Exam will be ALL free response Review materials are posted and you will have Friday’s class to ask any questions Parallel Circuits Homework is due Thursday

Wiring for Voltage 4.2.5 Parallel Circuits

Definitions parallel circuit – a circuit in which two or more elements are connected so that each has its own current loop.

Parallel Circuit Rules equivalent Resistance –> more resistors = less resistance 1/Req = 1/R1 + 1/R2 + … current – currents add up I = I1 + I2 + … voltage – voltages same for each resistor V = V1 = V2 = … All circuit components and the circuit as a whole must obey Ohm’s Law

Junction Rule The total current flowing into and out of a junction must be the same 10 A 6.0 A ? 4.0 A

Junction Rule 6.0 A 10 A 6.0 A ? ? 4.0 A 2.0 A

R1 = 30 Ω R2 = 30 Ω R3 = 30 Ω 60 V V (V) I (A) R (Ω) R1 R2 R3 Req 60 2.0 30 60 2.0 30 60 2.0 30 60 6.0 10

R1 = 20 Ω R2 = 50 Ω R3 = 10 Ω 0.5 A V (V) I (A) R (Ω) R1 R2 R3 Req 5.0 0.25 20 5.0 0.1 50 5.0 0.5 10 5.0 0.85 5.9