Download Activity 2

ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 1
Lesson 1 Understanding electric magnitudes
Activity 1
Watch the power point presentation about the hydraulic analogy of electricity.
Now check the hydraulic analogy at your school.
Voltage: look at the pressure indicator on the fire-prevention hose at different
floor levels of your school. Now build a sentence, choosing the suitable words.
The water pressure (voltage)
increase
as you
decrease
is the same whatever floor you are on
go up
go down
Because
upstairs
the potential energy of water
downstairs
is higher
is lower
is the same
Resistance and Intensity: look at any water tap. Obviously, as it is closed no
water can flow. Now open it slowly and observe that, as you open it more,
water can flow.
Summarize your observations and its analogy with electric circuits by filling the blanks in the
text below with suitable words from the word bank. Be careful because there are more words
than blanks to fill. Some could be used more than once.
obstruction open tap resistance copper infinite cork water decreases increases intensity as
pass circuit
The tap is an _________ for the water circuit as the electrical_________ is an obstruction for
an electrical _________.
If the _________ is closed (infinite obstruction) no _________ can flow. If the electrical
resistance is _________ (open circuit or we put insulating materials like_________, plastic,
rubber, etc.) no electricity can _________.
As we _________ slowly the _________ the obstruction _________ and the water begins to
flow. As we decrease the obstruction the flow____________. If we put less insulating materials
(water, graphite, rust iron, steel, aluminium, _________, etc.) we see that _________ the
obstruction decreases the _________ of the current increases.
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ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 1
Activity 2
Watch, read, listen to and repeat the slides and questions in the following
internet presentations about electric voltage or potential difference (dp) What
happens if the electric voltage increases in a simple circuit?
http://www.bbc.co.uk/schools/scienceclips/ages/8_9/circuits_conductors_fs.shtml
Copy the question and correct answer or complete sentence from the quiz.
5)
6)
7)
8)
Now assemble a simple circuit with wires, switch and light bulb but use a
variable power supply. What happens if we increase the voltage slowly from
zero to the full voltage the bulb can tolerate?
Summarize your observations writing some sentences using the structures proposed below.
The first sentence it is already done as example
Voltage
The bulb
zero
¼
½
¾
Full
has a very
bright light
has a normal
light
doesn’t light at
all
has a bright
light
has a dimly
light
is very hot
is slightly hot
is cold
is hot
is warm
1) When the voltage is zero, the bulb doesn’t light at all and it is cold
2) When the voltage is_________, the bulb_________________ and it is __________
3)
4)
5)
2/30
ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 1
Activity 3
Watch, read, listen to and repeat the slides and questions in the following
internet presentations about electric resistance. What happens if the electric
resistance increases in a simple circuit?
http://www.bbc.co.uk/schools/scienceclips/ages/10_11/changing_circuits_fs.shtml
Copy the question and correct answer or complete sentence from the quiz
1)
2)
3)
4)
5)
6)
7)
8)
9)
10)
Now assemble a simple circuit with a battery, wires, switch and a light bulb. Now
add another bulb between the last one and the power supply. Finally add a 3rd lit
bulb. What can you observe? Now remake the circuit adding a very long, long
wire, adding more switches, etc.
Voltage
one bulb
two bulbs
three bulbs
Three bulbs, long wires and
several switches
brightness
picture
Resistance
small
Summarize your observations writing some sentences using the structures proposed below.
The first sentence it is already done as example.
The bulb/s
has/ have
a dimly light
has/ have
a bright light
doesn’t/ don’t
light at all
has/ have
a normal light
is/are warm
is/are hot
is/are very hot
is/are cold
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ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 1
1) When the circuit has one bulb, the bulb has a bright light and is very hot.
2) When the circuit has _____ bulbs, the bulbs have a _______light and are ________
3)
4)
The
resistance is
The highest
resistance
The smallest
resistance
small/medium
high/very high
with
just one bulb
two bulbs
three bulbs
happens with
just one bulb
two bulbs
three bulbs
and
a long wire
a short wire
1) The resistance is _________________________ with ________________________.
2) The resistance is _________________________ with ________________________.
3) The resistance is _________________________ with ________________________.
The highest resistance happens with ____________________ and______________________
The smallest resistance happens with ____________________ and______________________
4/30
ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 2
Lesson 2 Electric measurements
Activity 1
You have to get into teams of two. Read the summarized transcription
about how to use a multimetre while you. Then listen to the presentation
on http://www.youtube.com/watch?v=KzjMIcER4EU
As a 1st member of your team explain the meaning of the words written
below. You can use the presentation transcription, a monolingual on-line dictionary.
http://dictionary.cambridge.org/ or an on-line encyclopaedia http://en.wikipedia.org/
Measurement is ______________________________________________________________
Gauge is ____________________________________________________________________
Continuity is _________________________________________________________________
Resistor code is ______________________________________________________________
Probes are __________________________________________________________________
Range is ____________________________________________________________________
As a 2nd member of your team, answer the following questions? Remember to begin an answer
using the question..
What is a multimetre? A multimetre is…
How do you use it? I/We use it ___________________________________________________
How to measure continuity? We measure continuity __________________________________
How to measure voltage? _______________________________________________________
How to measure current? _______________________________________________________
Activity 2
You have to get into teams of four/five. Each student in the group
receives a slip of paper with part of the instructions about how to
use a multimetre. There are some missing words on each slip that
you have to fill in with the words from the word bank below.
 First read your slip and try to fill in the gaps.
 Now read your slip to your group and ask them to help you check/fill the gaps.
 Then the group works out the correct order of the text.
 Next
listen
to
the
proposed
order
of
instructions
other
groups
have
and
agree/disagree/correct ‘til all the class agree on the order.
 Finally each group writes a question about the text and asks/answers questions with other
groups.
5/30
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
Activity 3
You have to get into teams of two. First write down the multimetre parts on the picture.
Display, On/Off button or position, Voltmeter AC, Voltmeter DC
Ohmmeter, Ammeter DC, Ammeter AC, Continuity, Common
jack, Volt/Ohm jack, Amp jack, Selecting wheel, Other(diodes)
Now draw two probes, one red and one black and set them to the jack/s that they can be
connected to.
Finally compare this multimetre with the multimetre you have in your technology
workshop. Explain the similarities and the differences you have found: number of jacks,
Measurements able to do, screen pictures, etc.
Picture multimetre
Technology workshop multimetre
Similarities
Differences
6/30
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
Activity 4
Continuity test. No power supply is needed for
continuity test, because the multimetre provides the
required energy and also works as a buzzer.
The continuity test checks if electricity can pass
through an electric component, this is if a connection between two
points of the circuit exists.
Set the red probe to VΩ. Set the measuring wheel (knob) to Ohm, musical note. If necessary,
press function button to make musical note appear on the metre screen.
Now experiment with the metre and choose/write the answer
a) Check if the continuity test works by linking the probes.
ANSWER: If the metre beeps, it’s OK/it works/it is working/it is correct.
b) Check if a spare wire is OK.
ANSWER: If the metre beeps/doesn’t beep, it’s OK/it works/it is working/it is correct.
c) Check if a wire within the circuit is OK. ANSWER:
d) Check if a switch in on position is OK. ANSWER:
d) Check if a switch in on position is OK. ANSWER:
Think what problem is happening when the multimetre beeps/doesn’t beep at the right position.
Activity 5
Resistance measurement. No power supply
is needed for this test, because Ohmmetre
provides the required energy. The
multimetre works as a Voltmetre and an
Ammetre together, using the Ohm’s law to calculate
Resistance.
The Ohmmetre measures the opposition that substances have against the flow of electricity.
Instructions: Set the red probe to VΩ. Set the measuring wheel (knob) to Ohm. Choose the
gauge according with the expected resistance value. Big resistance use M for MegaOhms (106
Ohms). Small resistances use Ohms.
Sample
Selected gauge
Measure
Insulator or Conductor?
Spare wire
Bulb 12 V
Bulb 230 V
A key
Dry finger
Wet finger
Dry wood
Wet wood
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Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
Activity 6
Voltmeter measurement. To measure voltage, circuit needs
power supply. The Voltmetre has a big resistance.
It measures the potential difference between two points of the circuit,
which means the energy that electrons loss when they pass through an
electrical component. It is used to measure the voltage effect of each
electric component.
Look at the following circuits diagrams used to measure voltage.
Voltmeter serial at the battery
Voltmeter parallel at the bulb lit
Voltmeter serial at the bulb light
Voltmeter parallel at the battery
Voltmeter serial at the switch
Voltmeter parallel at the switch
Which of them do you think are wrong / correct / useless? Justify your decision.
Will the bulb light up or not, Will the main current will through the bulb circuit or the
meter, Will the multimetre reading be high/normal/low, etc.
The first is already done:
The top left diagram (Voltmeter series at the battery) is incorrect because in this disposition
Voltmetre, as it has high resistance, prevents current from flowing through the bulb. The bulb
will not light on, and the multimetre reading will be useless.
8/30
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
Now, it’s your turn:
The top middle diagram (Voltmeter parallel at the bulb) is______________________________
The top right diagram (Voltmeter serial at the bulb) is_________________________________
The bottom left diagram (Voltmeter parallel at the battery) is____________________________
The bottom middle diagram (Voltmeter series at the switch) is___________________________
The bottom right diagram (Voltmeter parallel at the switch) is___________________________
Now assemble the circuits respecting the voltage prescribed by your teacher
and check if your predictions are true. Check for each assembly if the light bulb
turns on and off. Use a Voltmetre to measure.
Instructions: Set the red probe to VΩ. Set the measuring wheel (knob) to DCV: Direct current
voltage. Choose the gauge according with the expected voltage value.
Write down your measurement inside each picture above.
Complete comparative sentences about the voltage values obtained in circuits where the bulb
turns on. (the same, highest that, smaller than, slightly highest than)
The voltage measured at the battery is ________________ the voltage measured at the bulb.
The voltage measured at the bulb is __________________ the voltage measured at the switch.
The voltage measured at the switch is ________________ the voltage measured at the battery.
Finally write a summary about multimetre use and safety.
For measuring the circuit/bulb/battery voltage... you must/mustn’t
1)
2)
3)
9/30
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
Activity 7
Ammetre measurement. To measure intensity, circuit needs
power supply. The Ammetre has a very small, nearly zero,
resistance,
It measures the flow of current through a part of the circuit, which
means how many electrons pass at a given time at a point. It is used to
know the current passing through a section of the circuit.
Look at the following circuits diagrams used to measure intensity.
Ammeter serial at the battery
Ammeter parallel at the battery
Ammeter parallel at the bulb
Ammeter serial at the switch
Ammeter serial at the bulb
Ammeter parallel at the switch
Which of them do you think are wrong / correct / useless? Justify your decision.
Will the bulb light up or not, Will the main current will through the bulb circuit or the
meter, Will the multimetre reading be high/normal/low, etc.
The first is already done:
The top left diagram (Ammetre serial at the battery) is correct because in this disposition
Ammetre, as it has a very small resistance, allows current to flow through the bulb. The bulb
will light on, and the multimetre reading will be normal, measuring current passing
through the circuit.
10/30
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
Now, it’s your turn:
The top middle diagram (Ammetre parallel at the bulb) is_______________________________
___________________________________________________________________________
The top right diagram (Ammetre serial at the bulb) is_________________________________
___________________________________________________________________________
The bottom left diagram (Ammetre parallel at the battery) is____________________________
___________________________________________________________________________
The bottom middle diagram (Ammetre series at the switch) is___________________________
___________________________________________________________________________
The bottom right diagram (Ammetre parallel at the switch) is____________________________
___________________________________________________________________________
Now assemble the circuits respecting the voltage prescribed by your teacher
and check if your predictions are true. Check if the lit bulb turns on and off. Use
an Ammetre to measure.
Warning: Be very careful because some of the circuits are dangerous (shortcircuit) if
connected over very low voltage. If possible use a power supply unit instead of a battery.
Instructions: Set the red probe to A. Set the measuring wheel (knob) to DCA: Direct current
Intensity. Choose the gauge according with the expected intensity value.
Write down your measurement inside each picture above.
Why intensity measurements are always the same on circuits where the bulb turns on?
ANSWER: ___________________________________________________________________
Finally write a summary about multimetre use and safety.
For measuring the circuit/bulb/battery intensity... you must/mustn’t
1)
2)
3)
11/30
ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 2
Activity 8
Choose the explanation that fits better with each possible measurement the multimetre
(meter) can do. Series: meter inside the only possible electricity path Parallel: meter in
a different electricity path.
Measurement
Circuit diagram with
metre, series or parallel
Power on circuit?
How the meter
works
Big resistance
Voltmeter
Small resistance
Circuit power on
A battery and a
buzzer
Ammeter
Circuit power off
Continuity
A battery with a
Voltmetre and a
Ammetre working
together
Power off & isolated element
Ohmmeter
Now summarise information with a sentence for each measurement. The first is already done...
The Voltmetre works with circuit power on. The Voltmetre has a big resistance, so it must be
connected in parallel with the element we are going to measure.
The Ammetre works ___________________________________________________________
___________________________________________________________________________.
The Ohmmetre works __________________________________________________________
___________________________________________________________________________.
The Continuity test works _______________________________________________________
___________________________________________________________________________.
Activity 9
Ohm’s law: assemble a simple circuit using a variable power supply station and a
meter to measure both voltage and intensity. Do measurements and take records as
the voltage slowly increases from zero to the full voltage tolerated by the bulb.
Power supply
voltage
Voltmeter at
the battery(V)
Voltmeter at
the bulb (V)
Zero
¼ ( V)
½( V)
Ammeter (A)
12/30
¾( V)
full( V)
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
Measure the resistance of the bulb alone (0 voltage) with the Ohmmeter.
Use the Ohm’s law Voltage (V) = Resistance (Ω) x Intensity (A) to calculate the resistance of
the bulb and check if the Ohm’s law is fulfilled
Power supply
Zero
¼ ( V)
½( V)
¾( V)
full( V)
voltage
Measured
Calculated resistance using Ohm’s law. R = V/I
resistance
Bulb’s
resistance (Ω)
According with your observations, complete the sentences using increases /decreases
/remains the same.
If the Voltage increases the bulb’s resistance _________________.
If Intensity decreases, the bulb’s resistance __________________.
Activity 10
Expand the table you did in the previous activity to fill in the information you can
calculate about energy and power in your basic circuit. Remember the Power and
Energy formulas you already know:
Electric Power (W) = Voltage (V) x Intensity (A)
Energy consumed or Work (kW.h) = Electric Power (W) x time working (hours)
Power supply voltage
Zero = 0 V
¼ =___ V
Power (W)
Daily (24h) consume
of Energy (Kw.h)
13/30
½ =___ V
¾ =___ V
Full =___ V
ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 2
Activity 11
Electric appliances and light bulbs always give information about the voltage
required to work properly and the power they provide at the given voltage. With
the compulsory advice of your parents & teachers analyse at least 12 electric
appliances and lights at home or at school and record the voltage and power
information. Most electrical appliances have the required information in a plate on its back or in
the instructions leaflet.
Now calculate the rest of electrical magnitudes for each one, including consumption if they are
connected for a whole day: 24 hours.
The first is done as an example.
 a 100 Watts bulb working at 220 Volts has a current of I(A)=P(W)/V(V)=100W/220V = 0,45A
 The bulb resistance according to Ohm’s law is R (Ω) = V(V)/ I(A) = 220 V/ 0,45A = 485 Ω
 The daily energy consumed is E (kW.h) = P (kW) x time (hours) = 100 W* 1Kw/1.000W *
24 h = 2,4 kW.h. Remember to convert W into kW by dividing by 1000!
Fill in the table with the information recorded and calculated. Suggestion: You can use a
processing sheet (Excel) to calculate the results.
Electric
components
Voltage use (V)
Incandescent bulb
220
100W
Incandescent bulb
220
60 W
Incandescent bulb
40 W
Energy saving bulb
12W
Power
provided
(W)
100
Calculated Calculated
Daily
Intensity Resistance consume of
(A)
(Ω)
Energy (Kw.h)
P/V = 0,45
V/I = 485
P*t/1000 = 2,4
Blender
Washing machine
Fridge
Television “Telly”
Computer
Other appliances: DC bulb, dish washer, hair dryer, clothes dryer, toaster, HI-FI, wide screen,
console, printer, speakers, radio, microwave, oven, freezer, fan, electric radiator, heater, radio,
air conditioned, etc.
14/30
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
According with your observations complete the sentences using: increases, decreases,
remains the same
{Resistance...
For a given voltage, if Power increases, then {Intensity...
{Energy consume...
{Energy consume...
For a given voltage if Resistance increases, then {Intensity...
{Power...
Discuss results with your partner and justify your observations. You can use the Water circuit
analogy to clarify your ideas.
Activity 12
Take an old electricity bill from home. Cut out the information about your account and
bank where the bill is charged. Now analyze the information provided on the bill.
a) You pay for the right to have electricity: the power payment. (‘Potència’) This is a fixed
amount for each kW you can use, even if you are not using it because you are on holiday.
The device that controls your power limit is called Main Switch or Main circuit breaker (ICP
“Interruptor de Control de Potència”) If you overload your fitting, the ICP disconnects all your
appliances and lights.
How many kW can you use at home? How much does it cost?
Available power in kW at
Daily kW cost
Number of days
home
15/30
Total cost in bill
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 2
b) You pay for the electricity you use: the energy payment. (‘Consum’) This is a variable
amount depending on how many kWh you really use. If you are on holiday, you don’t pay
anything, except for the fridge...
The device that controls your consume is called electric meter. (“comptador electric”) The more
energy you consume, the highest measurement the meter will record and the more expensive
your energy payment will be.
How much does it cost? Calculate the cost of each kW.h
Electricity used in kW.h
kW.h cost
Total cost in bill
Now calculate the cost of some bulbs and electrical appliances at home if they are connected on
all the day along.
Bulb or
Incandescent Energy saving
Computer
Telly
Fridge
appliance
bulb 60 W
bulb 12W
Daily cost in €
Do you think it is worthwhile switching the bulbs and appliances off when you aren’t using
them?
16/30
ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 2
Activity 13
All the units we use to measure electricity and energy are called after the people who
discovered and explained the electricity phenomenon or invented any electricity device.
Search them on the Internet.http://en.wikipedia.org/wiki/International_System_of_Units
Look also for important people who do not have a unit named after them: Benjamin Franklin,
Thomas Alva Edison, Luigi Galvani, etc. What is the character you like the most? Why?
Now choose two of them and search for biography information on the Wikipedia or other
Internet sites. http://www.energyquest.ca.gov/scientists/index.html
Here you have an example with questions you can answer for each one...
What is his/her forename and surname? What was his/her nationality?
Georg Simon OHM. German
When and where did he/she live?
1789-1854. Bavaria, Germany.
What was he/she studying at the time of his/her achievement?
He was working as a Mathematics teacher in The Jesuit Gymnasium of Cologne where he was
experimenting on physics in the physics laboratory.
What did he/she discovered, explained or invented?
He discovered the Ohm’s law. Ohm's law states that the current through a conductor between
two points is directly proportional to the potential difference (i.e. voltage drop or voltage) across
the two points, and inversely proportional to the resistance between them.
The mathematical equation that describes this relationship is I = V/R where I is the current, V is
the potential difference in volts, and R is a circuit parameter called the resistance (measured in
ohms, also equivalent to volts per ampere)
Was his/her achievement useful at his/her time?
His work greatly influenced the theory and applications of current electricity at that moment.
Did he/she get any recognition for his/her achievement?
At first Ohm's work was received with little enthusiasm. However, his work was eventually
recognized by the Royal Society with its award of the Copley Medal in 1841. He became a
foreign member of the Royal Society in 1842, and in 1845 he became a full member of the
Bavarian Academy of Sciences and Humanities.
Was he/she in contact, sharing or arguing with other electricity researchers at his/her
time? Which ones and about what?
He drew considerable inspiration from Fourier's work on heat conduction in the theoretical
explanation of his work.
You can also write a 4-5 sentences summary with all the information about your character or
complete a table like this:
Character
and
profession
Georg
Simon
OHM.
Teacher
When and
where did
he live?
1789-1854.
Bavaria,
Germany.
He is Famous for...
Prizes, titles,
memberships,...
He discovered the Ohm’s law: the current Member of Bavarian
through a conductor is directly proportional to Academy. Royal Society
the voltage, and inversely proportional to the member and medal.
resistance. I =V/R
17/30
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 3
Lesson 3 Series and parallel circuits
Activity 1
Read the following diagram about a series resistor circuit. Think about what will
happen with voltage, intensity and resistance when we increase the number of bulbs in
series.
Write 4 sentences with your predictions: increases /decreases /remains the same =
In a series circuit, as the number of bulbs increase, I think...
The circuit voltage___________________________
The circuit intensity__________________________
The circuit resistance_________________________
The bulbs light... goes dimmer / stays the same / goes brighter
Now assemble the circuit using only a bulb, then two and finally three bulbs with the
same power in series.
Use a multimetre to measure the voltage and current of the circuit. Calculate the circuit
resistance also.
Record the measurements in a table:
Series
bulbs
Measured Voltage
at one bulb V1
Measured Voltage
at the battery VT
Measured Intensity
at any point I1, IT
Calculated Resistance
of one bulb R1
Calculated Resistance
of the circuit RT
zero
one
18/30
two
three
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 3
Correct your predictions according to your observations and measurements.
What will happen to the circuit if one bulb goes out? Check it.
Now read the series circuit laws and check if your circuit follows them by replacing the
measurements in the equations.
We use the same type of bulb so all have the same Resistance R = R1 = R2 = R3
VT = V1 + V2 + V3
IT = I1 = I2 = I3
RT = R1 + R2 + R3= 3R
Remember that Ohm’s law always works either with one bulb or the entire circuit. Replace the
measurement in the equations
VT = RT x IT
V1 = R1 x I1
V2 = R2 x I2
V3 = R3 x I3
Reporting
Write a report of the serial circuit using the model provided by your teacher. Remember
to attach some photos and diagrams. Use your corrected predictions as conclusions.
Activity 2
Read the following diagram about a parallel resistor circuit. Think about what will
happen with voltage, intensity and resistance when we increase the number of bulbs.
Write 4 sentences with your predictions: increases /decreases /remains the same =
In a parallel circuit, as the number of bulbs increase, I think...
The circuit voltage___________________________
The circuit intensity__________________________
The circuit resistance_________________________
The bulbs light... goes dimmer / stays the same / goes brighter
Now assemble the circuit using only a bulb, then two and finally three bulbs with the
same power in parallel.
19/30
Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 3
Use a multimetre to measure the voltage and current of the circuit. Calculate the circuit
resistance also.
Record the measurements in a table:
Parallel
bulbs
Measured Voltage
at one bulb V1
Measured Voltage
at the battery VT
Measured Intensity
at one bulb I1
Measured Intensity
at the battery IT
Calculated Resistance
of one bulb R1
Calculated Resistance
of the circuit RT
zero
one
two
three
Correct your predictions according to your observations and measurements.
What will happen to the circuit if one bulb goes out? Check it.
Now read the parallel circuit laws and check if your circuit follows them by replace the
measurements in the equations
We use the same type of bulb so all have the same Resistance R = R1 = R2 = R3
VT = V1 = V2 = V3
IT = I1 + I2 + I 3
1/RT = 1/R1 + 1/R2 + 1/R3
RT = R/3
Remember that Ohm’s law always works either with one bulb or the entire circuit. Replace the
measurement in the equations
VT = RT x IT
V1 = R1 x I1
V2 = R2 x I2
V3 = R3 x I3
Reporting
Write a report of the serial circuit using the model provided by your teacher. Remember
to attach some photos and diagrams. Use your corrected predictions as conclusions.
20/30
ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 3
Activity 3
Compare the series and the parallel resistor circuit you have just seen. Think about
advantages and disadvantages of each one according to the length and quantity of
wires required, the consequences of a bulb going out, the easiness to locate
breakdowns, the consequences of using different power bulbs, etc.
Issue
Serial circuit
Parallel circuit
Number of wires
required (more /less)
If a bulb goes out,
the circuit...(still
works / doesn’t work)
To locate breakdowns
is... (easy /difficult)
When we add
resistors the total
Voltage...
=
When we add
resistors the total
Intensity ... ↑↓ =
When we add
resistors the total
Resistance... ↑↓ =
When we add
resistors the total
Power... ↑↓ =
more
circuit
more
circuit
more
circuit
more
circuit
If we use different
power bulbs...
Other observations
Check your records with other students. Discuss and reach an agreement. Now use your
statements to think what is the best circuit for using in industrial and/or residential electric
installations? Justify your answer.
Now look for a real example of a series circuit and a parallel circuit
An example of a serial circuit is…
An example of a parallel circuit is…
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ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 3
Activity 4
a) Read carefully
the following circuit
diagram
and
assemble it.
b) Write down the name of
each
electric
component
beside its number
c)Turn the switches on and off and write down what you observe for each of the four possible
switch combinations. What bulbs light on?.Have they a bright or dim light? Is this a simple
/series /parallel or mixed circuit?
Redraw the simplified diagram of the lighted bulbs
Switch
2 down
3 off
2 up
3 off
2 down
3 on
2 up
3 on
Bulbs on,
brightness
Circuit type
Equivalent
simplified
diagram
.d) Now think what happens in each combination. With the switch 2 up / down and switch 3
off/on, the resulting circuit is simple/series/parallel/mixed, so...
number 4
The
bulb
number 5
is cold / warm / hot / very hot
...
has a dim / normal / bright light/doesn’t light up at all
number 6
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Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 3
Here you have an example
1) With 2-way switch up and simple switch off, the resulting circuit is simple. The bulb 5 is
very hot and has a bright light.
2) With
3) With
4) With
e) Now use a multimetre to measure the voltage and current of the circuit. Calculate
the circuit resistance and power. Record the measurements in a table. Repeat the
measurement for each possible combination of switches.
2-way up,
Simple off
2-way down
Simple off
2-way down
Simple on
Measured Voltage Vt
provided by the Battery
Measured Intensity It
through the Battery
Calculated Circuit
Resistance Rt
Calculated Circuit Power
The most powerful circuit is_____________________________________
The highest resistance circuit is__________________________________
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2-way up
Simple on
ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 3
Activity 5
Revise the slides and questions in the following internet presentations about
serial batteries. What happens if we connect several batteries in series?
http://www.bbc.co.uk/schools/scienceclips/ages/8_9/circuits_conductors_fs.shtml
Assemble a simple circuit with wires, a switch, a light bulb and a battery. Make
sure you use a battery with a voltage about half of the required voltage of the
bulb. Use a multimetre to measure the voltage and current of the circuit.
Calculate the resistance of the light. Now increase the number of batteries, up
to three, placing them in series (one battery after the other following the same wire path)
Record the new measurements in a table:
Series
batteries
Measured
Voltage at bulb
Measured
Voltage at one battery
Measured
Intensity
Calculated
Resistance of bulb
zero
1
2
3
Summarise your observations
As we increase the number of series batteries...
The voltage....
The intensity...
The resistance...
Series batteries are used for.....
Draw the serial batteries circuit diagram, including how you place the multimetre to measure.
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Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 3
Now assemble a simple circuit with wires, a switch, a light bulb and a battery. Use a multimetre
to measure the voltage and current of the circuit. Calculate the resistance of the light. Now
increase the number of batteries, up to three, placing them in parallel: each battery has its own
different wire path (all paths link to the bulb and to the switch) Record the new measurements
in a table:
Parallel
batteries
Measured
Voltage at bulb
Measured
Voltage at one battery
Measured
Intensity at one battery
Measured
Intensity at bulb
Calculated
Resistance of bulb
zero
1
2
3
Summarise your observations.
As we increase the number of parallel batteries...
The voltage....
The intensity...
The resistance...
Parallel batteries are used for.....
Draw the parallel batteries circuit diagram, including how you place the multimetre to measure.
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ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 4
Lesson 4 Revision on electricity
Activity 1
Watch and read the following cartoon link about what life in a Victorian House
by the end of XIX century was like. Look how they washed clothes, heated
and lit the house.
http://www.bbc.co.uk/education/dynamo/history/stepback.htm
Complete the information searching on the Internet. Describe the following pre-electrical light
devices: bonfire, hearth, torch, candle, oil lamp, paraffin lamp, gas lighting.
What kind of combustible did they use? How much light did they produce? How safe was the
device? How easy to manage was the device? How much did the combustible cost?
Order all of them including the electrical bulb pointing at their advantages and inconveniences.
Device
Century
Advantages
Disadvantages
Still in use?
Where and when
bonfire
hearth
torch
candle
oil lamp
paraffin
lamp
gas
lighting
light bulb
Search for photos or pictures of the different lighting techniques in order to illustrate and
complete your table.
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Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 4
Activity 2
Electricity word search.
Find the following words in the puzzle:
ammeter battery bulb cell current electricity lamp motor ohmmeter resistor switch
voltmeter wire
Activity 3
Memory game. Electric components: name, symbol and use.
Play the game in groups of 2-4 students. Mix all the cards. Then display them
all face down in rows and columns. The first player chooses a card and turns it
over and reads/shows the card. Then he does a second and a third card
choice and also turns them over. If the three cards match, the player keeps them with him and
scores 1 point. If they don’t match, he arranges them face down to their former places. Now it’s
the second player’s turn. Once all the cards have been paired up, the player with more points
wins. Below you have a sample of three cards that match.
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Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 4
A transducer which
converts electrical
energy to light.
Lamp (bulb)
Activity 4
Look for electric appliances around you at school and at home. Write their name and
link them with the sort of energy they produce. Some appliances convert electricity to
more than one energy type.

Electrical appliances
Bulb
Energy conversion
 Light


 Sound


 Heat waste


 Movement


 Heat use


 Noise
Activity 5
Connect to the following links to play quiz games about energy and electricity. A quiz is
a contest between two teams where you have to answer questions beginning with a
given letter. You will see the instructions displayed on the internet site.
http://www.teachers-direct.co.uk/resources/quiz-busters/quiz-busters-game.aspx?game_id=294
http://www.teachers-direct.co.uk/resources/quiz-busters/quiz-busters-game.aspx?game_id=225
http://www.teachers-direct.co.uk/resources/quiz-busters/quiz-busters-game.aspx?game_id=5594
http://www.teachers-direct.co.uk/resources/quiz-busters/quiz-busters-game.aspx?game_id=5027
http://www.teachers-direct.co.uk/resources/quiz-busters/quiz-busters-game.aspx?game_id=2076
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Ernest FERRER
ELECTRIC CIRCUITS
Activities. Lesson 4
Activity 6
Analyse the following circuits, where the bulbs are the same and the cells are the
same.
Which bulb will be the dimmest?
Which circuit will have the biggest current?
Write down the voltmeter reading in order, from highest to lowest.
Now analyse these four new circuits and answer..
In which circuit will the ammeter show the lowest reading?
In which circuit will the bulb(s) be brightest?
In which circuit will the ammeter readings be highest?
Write down the ammeter readings in order, from highest to lowest.
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ELECTRIC CIRCUITS
Ernest FERRER
Activities. Lesson 4
Activity 7
Complete the following electricity family tree. Ask your teacher or use a bilingual dictionary if you don’t understand a word.
Electricity
is a kind of
______
measured
magnitudes like
flow s through a
_____ w ith
sw itches
like
Primary
electric
converter
like
Intens ity
Voltage
through a device called ___________ w ith different meters
NC
sw itch
Converted
from
like______
motor
all three magnitudes related by _____ law
renew able
energies like
in Pow er
Plants
Ohmeter
w ater
dams
30/30