Week 6 Day 2

Units to be measured and calculated VoltageVoltsV or E ResistanceOhmsR or Ω Current AmpsI or A PowerWattW or P

Chapter 6 DIVIDER CIRCUITS AND KIRCHHOFF’S LAWS 6.1 Voltage divider circuits Kirchhoff’s Voltage Law (KVL) Current divider circuit Kirchhoff’s Current Law (KCL)

Chapter 7 Series Parallel Combination Circuits 7.1 What is a series-parallel circuit? Analysis technique Re-drawing complex schematics Component failure analysis Building series-parallel resistor circuits Contributors

5.3 Simple parallel circuits page 139 Experiment 6 Parallel circuits week 6.

Textbook page 139 The first principle to understand about parallel circuits is that the voltage is equal across all components in the circuit.

Chapter 6 page 193 Parallel circuits divide the total circuit current among individual branch currents.

Week 6 day 1 exercise.

The current is inverse to the Resistance.

Textbook page 146 For resistors in parallel total resistance is determined from the following equation:

Textbook page 141 The total circuit resistance in a parallel circuit is less than any one of the individual resistors.

Total resistance is less than the smallest resistance. Voltage is the same across all parallel components.

Measurements in parallel circuits.

MEASURING TOTAL CURRENT

MEASURING CURRENT IDIVIDUAL BRANCH L

Product / Sum

KCL Kirchhoff’s Current Law (KCL): ”The algebraic sum of all currents entering and exiting a node must equal zero” Textbook page 193

Is = I1 + I2 + I3 conventional flow

Textbook page mW 40.5mW 81mW = 129.6mW 5.5 Power calculations Power is additive in any configuration of resistive circuit: PTotal = P1 + P Pn

Redrawing a circuit.

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Voltage Sources in Parallel If for some reason two batteries of different voltages are placed in parallel, both will become ineffective or damaged because the battery with the larger voltage will rapidly discharge through the battery with the smaller terminal voltage.

Variable Resistor

Multiple current paths

Variable Resistor

Potentiometer Also called a pot; is a 3-terminal resistor with a sliding contact that forms an adjustable voltage divider. Rheostat Two terminals of a variable resistor are used with one end and the wiper acting as a variable resistor.

Potentiometer

Rheostat

We have created multiple current paths. This is a parallel circuit.

Short Circuits

Series parallel

Textbook page 198 Series Circuits: Voltage drops add to equal total voltage. All components share the same (equal) current. Resistances add to equal total resistance. Power is additive. (page 146)

Textbook page 198 Parallel Circuits: All components share the same (equal) voltage. Branch currents add to equal total current. Resistances diminish to equal total resistance. Power is additive. (page 146)

Page 199 We won’t be able to apply a single set of rules to every part of this circuit. We will have to identify which parts of that circuit are series and which parts are parallel, then selectively apply series and parallel rules.

The double slash (//) symbols represent ”parallel”

Page 202 The ”−−” symbol is used here to represent ”series,” just as the ”//” symbol is used to represent ”parallel.” (R1//R2−−R3//R4)