Resistors in Series and Parallel

Ch.10.5 pg 320-325

Welcome back!

• Please pick up your name plate

• Please pick up three handouts from the front:– Resistors in Series and Parallel– Problems with circuits with resistors– Current Voltage Resistance Review

AgendaGoal: Given a circuit, calculate- current (may change from resistor to resistor in parallel; remains the same in series)- voltage (may change from resistor to resistor in series; remains the same in parallel)- total resistance (increases with the number of resistors in series; decreases in parallel)

1. Questions about Ohm’s Law Lab2. Notes: Resistors in Series and Parallel3. Work on homework: Problems with circuits with

resistors4. Introduction and Co-creating cell phone rules

Important dates• Please take out your agenda write down these dates:1. Current Electricity Unit Test is on:

Feb 13th / Feb 16th

2. Ohm’s Law Lab is due on:section 1-2 on Feb 12th

section 2-2 on Feb 13th

3. If you missed Ohm’s Law Lab, make-up lab is on Wednesday, February 11th, during lunch in

W204

Questions about Ohm’s Law Lab

• Please take out Ohm’s Law Lab task sheet

Notes: Resistors in Series and Parallel1. Series Resistors: In a series circuit the same current is applied across each resistor but the voltage divides at each resistor.

IT = I1 = I2 = I3

VT = V1 + V2 + V3

RT = R1 + R2 + R3

The total resistance in a series circuit is equal to the sum of the individual resistances

Notes: Resistors in Series and Parallel

1. Parallel Resistors: In a parallel circuit, the voltage applied across each resistor is the same, but the current divides at each resistor.

IT = I1 + I2 + I3

VT = V1 = V2 = V3

= + +

The sum of the reciprocals of the resistances in a parallel circuit equals the reciprocal of the total resistance in the circuit RT

Summary TableType of Circuit Series Circuit Parallel CircuitTotal current (IT) IT = I1 = I2 = I3 IT = I1 + I2 + I3

Total voltage (VT) VT = V1 + V2 + V3 VT = V1 = V2 = V3

Total resistance (RT) RT = R1 + R2 + R3 = + +

Homework

• Worksheet: “Problems with circuits with resistors”

• After you are finished with worksheet and checked your answer, please work on “CURRENT VOLTAGE RESISTANCE REVIEW”

A few announcements

• Handout: introductions (if you don’t have one)

• When you come into class – Please read the instructions on powerpoint / whiteboards

• For your safety, please report to me when you come in late

• When I ask for your attention, I want to see:– Your eyes on me– Your hands free– Your lips sealed

• Washrooms: one person at a time, if possible– write your name in the corner of whiteboard

when you leave. Erase your name when you return

• Where to find handouts

• During labs: please put away your binders and bags under the tables on the sides

Electronic Devices Contract

• Please get into groups of 4-5

• On a large white paper, write down:– Your names– Make rules around using cell phones and

electronic devices in class– Consequences for keeping and breaking the

“contract”