8/13/2019 12_SPH0901N_Series and Parallel Circuits Lab.docx

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PhysicsHS/Science

Unit: 09 Lesson: 01

2012, TESCCC 10/30/12 page 1 of 3

Series and Parallel Circuits Lab

Introduction:

In the first part of this lab, use simple circuit boards to examine some of the properties of

resistors (light bulbs), in series and in parallel with each other. In these circuits, you are to

consider the bulbs as identical. In reality, quality control of simple flashlight bulbs is lacking, andif the properties are close, you should consider them as the same. You will be asked to measure

the voltage across bulbs and use the brightness of the bulbs to indicate the relative current flow

through the bulbs.

In the second part of the lab, build virtual circuits similar to the parallel and series circuit boards.

In these virtual labs, the circuit elements are perfect, and your decisions will be automatic.

Materials:

series and parallel circuit boards

single bulb with alligator clip leads

conductivity tester board multimeter

computer with Internet connection

printer

Part I: Series and Parallel Circuit Boards

The two circuit boards pictured each have two bulbs, a battery pack,

and a switch. Your circuits should be similar. Examine these circuits visually and with the

voltmeter to answer questions on the lab report. Compare and contrast the behavior of the two

circuits, specifically:

Judge the relative brightness of the bulbs on the two circuits and

a single bulb in the conductivity tester with a wire across the gap.

Measure the voltage across the bulbs in each circuit.

By screwing and unscrewing bulbs, determine the interaction

between the bulbs and ramifications for practical circuits.

Part II: Virtual Circuit Builder

Construct the circuits shown, and characterize the properties of these circuits. The open circles

are bulbs.

Visit the URL below, construct the circuits, and fill in the corresponding tables.

http://canu.ucalgary.ca/map/content/circuitbuilder/basic/simulate/practice/

Answer the questions on the Lab Report sheet related to these circuits.

Print a copy, or show your instructor each circuit with the meter values displayed.

http://canu.ucalgary.ca/map/content/circuitbuilder/basic/simulate/practice/http://canu.ucalgary.ca/map/content/circuitbuilder/basic/simulate/practice/http://canu.ucalgary.ca/map/content/circuitbuilder/basic/simulate/practice/

8/13/2019 12_SPH0901N_Series and Parallel Circuits Lab.docx

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PhysicsHS/Science

Unit: 09 Lesson: 01

2012, TESCCC 10/30/12 page 2 of 3

Series and Parallel Circuits Lab Report

Part I: Series and Parallel Circuit Boards

Rememberquality control for the bulbs is lacking, and close should be considered the same.

1. Compare the brightness of the bulbs in the conductivity tester (single bulb), two parallel

bulbs, and two series bulbs; list them from bright to dim.

2. Assuming the brightness is correlated with the current through the bulbs, summarize your

observation about the current through the bulbs.

3. What are the measured voltage values across the bulbs in each case? What do you

conclude?

4. As bulbs burn out or are unscrewed, how do the parallel bulbs react compared to the bulbs

in series with each other?

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PhysicsHS/Science

Unit: 09 Lesson: 01

2012, TESCCC 10/30/12 page 3 of 3

Part II: Virtual Circuit Builder

It is customary to designate circuit components with a symbol and subscript to identify one

resistor from another. In the series circuit, one could designate the bulb on the left as R 1, in

order to designate it as one resistor, and the other bulb as R2. The total resistance, as seen by

the battery, is normally referred to as the total resistance of the circuit, or RT. Use the circuit

values to fill in the voltage and current values in the charts below. Calculate the resistancevalues.

Bulbs in Series Circuit: Bulbs in Parallel Circuit:

Circuit

Element

Voltage

(volts)

Current

(amps)

Resistance

(ohms)

Bulb 1 V1= I1= R1=

Bulb 2 V2= I2= R2=

Battery VT= 10 IT= RT=

Resistanceis defined as R = V/I. Instead of

measuring the resistance, it is computed from the

voltage and current values. Show one example of this

calculation in the box.

1. Compare the total current from the battery for the series circuit to the total for the parallel

circuit. What pattern do you see in resistances and current?

2. Summarize any relationships, including equations, you see for the currents and resistances

for resistors, in series and in parallel, with each other. Note: Do not be afraid of getting the

wrong answer. Your focus should be on what is discovered. Your teacher will give you more

answers later.

Circuit

Element

Voltage

(volts)

Current

(amps)

Resistance

(ohms)

Bulb 1 V1= I1= R1=

Bulb 2 V2= I2= R2=

Battery VT= 10 IT= RT=