# 7J Electrical Circuits by dandanhuanghuang

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```									7J Electrical Circuits

Electrical energy, circuits and
solving problems.

More…

Tuesday, 27 March 2012                     1
INDEX
Lesson 1: How much do you know?
Lesson 2: Connecting basic circuits
Lesson 3: Electric current
Lesson 4: What do your results show? What if we used a different type of circuit?
Lesson 5: Series & Parallel. Dealing with the results. Where to put the ammeter.
Lesson 6: Resistance
Lesson 6b: Analysis
Lesson 8:
Lesson 9: Assessment

Tuesday, 27 March 2012                                         INDEX                 2
Lesson 1

How much do you know?

Tuesday, 27 March 2012          3
Equipment
BBC Revisewise DVD (orange disc)
BBC DVD – Class Clips 1
BBC DVD Wan2TlkScience
Old 4.5v battery (to show insides)
Mini whiteboards
Study guides (red, yellow & green)
Year 7 electricity MATs
Level MATs 4 & 5
Handouts
Generator demonstration

Tuesday, 27 March 2012                INDEX   4
Lesson objectives

 Refresh your learning from year 6.
 Discover ways in which ELECTRICITY is
 Refresh your skills in explaining how
and why things happen.

Tuesday, 27 March 2012   INDEX             5
A bit of input and a KEY QUESTION

   Revisewise DVD
CIRCUIT DIAGRAMS –
A reminder of what you
learnt last year.
   Key Stage 3 Bitesize.

Draw and label the circuit diagram symbols for the
following components:
 Light bulb (lamp)
 4.5 volt battery (make sure you get it right)
 switch
Tuesday, 27 March 2012                    INDEX                 6
… and a bit more

Draw a circuit diagram with a switch, a
battery and two bulbs. Set the diagram
out so that the switch will turn both
bulbs on together.

Tuesday, 27 March 2012           INDEX           7
More input

2. Some materials carry
electricity well. What name
do we give to materials
that carry electricity well?
‘Materials that carry
electricity well are called … ‘
1. BBC Class Clips
ELECTRICITY part 1                     3. Some materials are called
Wan2TlkScience.
electrical insulators. Explain
We will look at some of your work   what an ‘electrical insulator’
to judge how well you explained.    is.

Tuesday, 27 March 2012                          INDEX                    8
Power source

Power Station: A huge machine

What is a power station for?

To change the energy in mucky coal into
something more useful…

Electrical energy

Tuesday, 27 March 2012              INDEX      9
The power station converts the chemical
fuel energy into…

electrical
energy.
It’s and energy
conversion…
Chemical energy into
electrical energy.

Tuesday, 27 March 2012   INDEX                   10
Key Questions (use your study guide)
1. Some materials carry electricity well.    5.Draw and label the circuit diagram
What name do we give to materials that        symbols for the following components:
carry electricity well? ‘Materials that       · Light bulb (lamp)
carry electricity well are called … ‘         · 4.5 volt battery
2. Some materials are called electrical       · switch
insulators. Explain what an ‘electrical       · motor
insulator’ is.                                · buzzer
3. Draw a circuit that you could use in       6.Fossil fuels are the main energy sources
class to decide whether or not different      used to generate electricity. Name two
materials will carry electricity. Label the   fossil fuels, state why they are called ‘fossil’
diagram. Add a short paragraph to             and describe how the energy came to be in
explain how it works.                         these fuels. (Full sentences please! Could
4. Batteries are made from individual         even be a paragraph!)
cells. Dry cells produce 1½ volts each.       7.Draw a circuit diagram with a switch, a
How many cells make a 4½ volt battery.        battery and two bulbs. Set the diagram out
Explain how you know.                         so that the switch will turn both bulbs on
together.

Tuesday, 27 March 2012                                    INDEX                              11
Evaluation

 I am able to explain
clearly.
 My teacher will be able to
see that I understand.
marks out
 My drawings are                       of 5
accurate.

Tuesday, 27 March 2012      INDEX               12

Complete all the key questions.

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Lesson 2

Connecting basic circuits

Tuesday, 27 March 2012              14
Equipment
Study guides
Old 4½v battery to show 3 cells inside

Tuesday, 27 March 2012                    INDEX   15
Objectives

 To learn that batteries are made of
individual cells that are connected
together.
 To learn to identify faults in basic circuits.
 To check your ability to draw clear
diagrams.
 To revise drawing proper circuit
diagrams.

Tuesday, 27 March 2012         INDEX            16
What I am looking for

 Drawings that show each circuit before
and after the fault was mended.
 Clear drawings that show where the
wires are connected.
 Captions that describe what the
 Working quickly to finish the task.

Tuesday, 27 March 2012     INDEX            17
Safety

Old battery cells can
release nasty
chemicals.
Wash skin and
clothing if there is any
contact.

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Instructions
1. Find the page called ‘Basic Circuits’ in the study
guide.
2. Title & date.
3. Draw each circuit with its faults and again, with its
faults mended. Add a caption to each one. (Use
about ½ page for each pair). See example
4. Finally, draw each mended circuit as a circuit
diagram.

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Example            Your teacher will show you how to do this one.

back to
instructions

faulty circuit         mended circuit

circuit diagram                            caption

Tuesday, 27 March 2012                       INDEX                            20
Faulty circuits

INDEX
Evaluation

 I am able to draw very
clearly.
 I could easily see what
the faults were.
smiley
 I finished my work by the            faces
end of the lesson.

Tuesday, 27 March 2012         INDEX            22
Lesson 3

Electric current
see some

Tuesday, 27 March 2012                     23
Objectives…

 To learn how electricity flows in a circuit.
 To learn how to use an ammeter.
 To work together as a group.

Tuesday, 27 March 2012        INDEX               24
Teams

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By the end of the lesson…

You will have worked well in a team to:
 Make a table of results.
 Make a graph of the results.
 Written a description or an explanation of
how the number of bulbs affects the
current.

Tuesday, 27 March 2012      INDEX           26
Equipment
Transformers
Crocodile wires
Ammeters
2.2v bulbs
Study guides

Tuesday, 27 March 2012   INDEX   27
Safety

Electric wires can get very hot if
there is a fault.

Never connect anything directly to
the mains. (Shocking!)

Tuesday, 27 March 2012    INDEX       28
Input…

BBC Wan2Tlk Science
Circuits, conduction & components

Questions coming up…

Tuesday, 27 March 2012        INDEX   29
Millionaire

1.   The current flows around the circuit…
[A. Both ways, meeting in the middle]
[B. One way] [C. Nothing actually flows]
2.   The particles that move are called…
[A. Atoms] [B. Electricals] [C. Electrons]
3.   The more bulbs you add to a circuit…
[A. There is more resistance]
[B. There is less resistance]
[C. The current will not be affected]

Tuesday, 27 March 2012        INDEX               30
Measuring the current
You can use an ammeter to
measure the current in a circuit.

bulbs to the circuit,
will there be more
or less current?

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STUDY GUIDE:
Practical                 Current flow in electrical circuits.

+2v

X                                 Predict.
Which of these three circuits will
allow the most electricity to flow?

A
+2v

Explain why you think that.

B                                 Test.
+2v

Try all three circuits and get some
results. Try 4 bulbs too.

Tuesday, 27 March 2012                      INDEX                         32
End of lesson checklist and
 Table of results fixed into book.
 Graph.
 Description or explanation about how the
number of bulbs in the series circuit
affects the current.
 This must be completed as
HOMEWORK.

Tuesday, 27 March 2012     INDEX          33
Evaluation

 Our team worked well
together.
 We helped each other
with writing the
cheesy
explanation.
grins
 We all know how to use
the ammeter and get
decent results.

Tuesday, 27 March 2012      INDEX             34
Lesson 4

What if you used a different type of
circuit?

Tuesday, 27 March 2012                         35
Equipment
   Transformers
   Crocodile wires
   Ammeters
   2.2v bulbs
 Study guides
 Graph paper

Tuesday, 27 March 2012   INDEX   36
Objectives

 To learn that current is measured in
amps.
 To learn to look carefully at your results.
 To learn to design a graph that will show
 To learn that there are other ways to
build a circuit.

Tuesday, 27 March 2012       INDEX               37
Expectations

 You will decide if the number of bulbs
affects the current in the circuit.
 You will draw a graph that clearly
illustrates what you found out.
 You will build parallel circuits and
measure the current.

Tuesday, 27 March 2012      INDEX           38
Part 1
WORK IN PAIRS

 Look at your results. Does the number of
bulbs affect the current in the circuit?
[YES/NO]
 Design a statement that clearly states
how the number of bulbs affects the
current. [Write a sentence to read to the
class]

Tuesday, 27 March 2012      INDEX              39

What type of graph will
you draw?

Now draw graphs to

Tuesday, 27 March 2012              INDEX          40
Graph check list

•   The y axis is clearly calibrated.
• Both axes are labelled.
• The graph has a caption to describe
what it shows.

Tuesday, 27 March 2012           INDEX    41
Part 2: Building a different type of
circuit.
   This is a parallel circuit.
Try it, and measure the
current.
   Try 3 bulbs, even 4 if you
can.
   Plot a graph like the one
you did for the series
circuit.
   Compare the two graphs.
Write a short statement to
say what you noticed.

Tuesday, 27 March 2012             INDEX   42
Evaluation

 Current is measured in ______.
 Hold up your graph so that we can see
how clear it is.
 The two types of circuit are _____ and
_____.

Next lesson…
We will be sorting out why our two graphs were different.

Tuesday, 27 March 2012                          INDEX        43
Lesson 5

Series & parallel circuits
Dealing with the results
Deciding where the ammeter goes.

Tuesday, 27 March 2012                     44
Equipment
   Ammeters
   Crocodile wires
   Transformers
   2v bulbs
   Results tables
   Graph paper
   Mini-whiteboards, pens & erasers.
   DVD Wan2Tlk Science

Tuesday, 27 March 2012                   INDEX   45
Objectives

 Learn the differences between series
and parallel circuits.
 Learn how to use graphs to compare the
results effectively.
 Learn about where the ammeter fits in a
circuit.

Tuesday, 27 March 2012     INDEX             46
Expectations

 By the end of this lesson…
 You should know what series and
parallel circuits look like.
 You should know how to make a useful
 You should know where to put the
ammeter in a circuit.

Tuesday, 27 March 2012    INDEX           47
Part 1: Series & parallel

Work in pairs: Draw       Now draw a parallel
a series circuit with 3   circuit with 3 bulbs on
bulbs on one side of      the other side.
whiteboard.

Wan2Tlk Science: Series & Parallel Circuits
[BBC DVD]
Tuesday, 27 March 2012           INDEX                48
Part 2: Useful graphs: Results
Current in    Current in
series        parallel
Number of lamps        circuit       circuit

1           0.29          0.29

2           0.21          0.53

3           0.13          0.81

4           0.05          0.95

Tuesday, 27 March 2012         INDEX                49
Part 2: Useful graphs: Series

Current in series circuit

0.35

0.3

0.25                                           Current in series
current (amps)

circuit

0.2

0.15

0.1

0.05

0
1      2         3          4     num ber of lam ps

Tuesday, 27 March 2012                                 INDEX                             50
Part 2: Useful graphs: Parallel

Current in parallel circuit

1

0.9

0.8
Current (amps)

0.7
Current in
0.6
parallel circuit
0.5

0.4

0.3
0.2

0.1

0
1      2          3         4       Number of lamps

Tuesday, 27 March 2012                                  INDEX                         51
Part 2: Useful graphs: Comparison

Current in series and parallel circuits

1
0.9

0.8
Current in amps

0.7                                      Current in
0.6                                      series circuit

0.5                                      Current in
0.4                                      parallel circuit
0.3
0.2

0.1
0
1      2       3      4       Number of lamps

Tuesday, 27 March 2012                              INDEX                          52

Complete the two graphs.
Trim and fix them into your
book.

Tuesday, 27 March 2012   INDEX   53
Part 3: Investigating current
What difference will it make if the ammeter is placed in different places
on a series circuit? Group prediction.

Is the current different in different places around the circuit?

Tuesday, 27 March 2012                            INDEX                        54
Investigate

Work quickly as a team.
Write what you noticed into your book.
objectives

Tuesday, 27 March 2012              INDEX                55
Plenary

Reporting back

Up to five groups will be asked to

The objectives were…
Learn the differences between series and parallel circuits.
Learn how to use graphs to compare the results effectively.
Learn about where the ammeter fits in a circuit.

Tuesday, 27 March 2012                     INDEX                  56
Lesson 6

Resistance

Tuesday, 27 March 2012   57
Equipment
Long & thin resistance wires mounted on wood.
Ammeters.
Transformers or batteries.
2v light bulbs.
Graph paper.
Results tables.
Mini-whiteboards, pens & erasers.

Tuesday, 27 March 2012                       INDEX   58
Objectives

 Learn what electrical resistance is.
 Learn to work together to make
predictions.
 Learn to set up equipment quickly.
 Learn what is expected to explain at
level 5.

Tuesday, 27 March 2012      INDEX         59
Expectations

 By the end of the lesson…
 Work quickly and systematically to get
accurate results.
 Revise what you know about where to
put an ammeter.
 Write an explanation to explain what
happened.

Tuesday, 27 March 2012      INDEX           60
Making a prediction

Work in pairs

How does the length of the wire affect the current?

Write a prediction on your whiteboard.

Reporting back

Tuesday, 27 March 2012              INDEX             61
Safety

Thin wires can get hot!

Never connect directly to the mains
supply.

Tuesday, 27 March 2012     INDEX       62
Setting up                Work in groups of 4

1. Set up the
equipment as
shown in the
diagram. (The
‘roving wire’ is a
flexible
2. Observe what
happens to the
brightness of
the bulb if the
crocodile clip is
connected at
regular intervals
along the
resistance wire.

Tuesday, 27 March 2012   INDEX                        63
Measuring the current
3. Place an
ammeter in the
circuit. Measure
the current
(amps) when the
crocodile clip is
connected at
regular intervals
along the
resistance wire.
A
Where would
you put the
ammeter in
the circuit?

Tuesday, 27 March 2012   INDEX                       64
Input

Video clip explaining resistance.

Tuesday, 27 March 2012                INDEX   65
Results
Length of wire (mm)   Current (amps)

0

and so on…

Tuesday, 27 March 2012          INDEX        66
Plenary: Connections

Use whiteboards (one each if possible)

   Describe how the length of the thin wire
affects the current in the circuit.

Tuesday, 27 March 2012        INDEX             67

Use graph paper to make a clear graph of

Due: Next lesson

Take home your results & a sheet of graph paper. You may use a
computer if you have one.

Tuesday, 27 March 2012                    INDEX                   68
Lesson 6b

Explanations

Tuesday, 27 March 2012   69
Objectives

 To use your results and graph to write a
clear explanation.
 To try to write at level 5.

Tuesday, 27 March 2012      INDEX             70
Check list

In your book, you should have:

 Some writing that describes how the
length of the wire affects the current.
 A graph that clearly shows the
relationship between the length of the
wire and the current.

Tuesday, 27 March 2012       INDEX           71
Level 4
Writing at level 4

Level 4
You can use scientific
knowledge and words to
describe what happens

Tuesday, 27 March 2012   INDEX   72
Level 5
Writing at level 5

Level 5
You can use a higher level of scientific knowledge and words
to explain and describe what happens

You can begin to explain How or Why things happen in terms
of either Energy, Forces, Particles or Cells

Tuesday, 27 March 2012                                     INDEX   73
Analysis
Length of     Current   3. Use your whiteboard to
wire (mm)     (amps)
draft an explanation.
0
4. Listen to other people’s
explanations.

5. Copy (redraft) your
explanation into your
and so                 book.
on…

Tuesday, 27 March 2012              INDEX                74
Plenary
PAIRS

 The main new thing I learnt was…
 What I didn’t really understand was…
 I am a bit clearer about…
 My conclusion was level…
 The most interesting part of the lesson
was…

Tuesday, 27 March 2012      INDEX            75
Electricity Lesson 7

Solving electrical problems

Tuesday, 27 March 2012                76
Equipment

Battery modules
6v bulbs, crocodile wires & switches.
Dimmers
Motors & buzzers
Diodes & reed switches

Tuesday, 27 March 2012      INDEX        77
Starter

Work in a group of 4.
Get two bulbs, a battery and a switch.
Make a parallel circuit for the two bulbs.

Tuesday, 27 March 2012           INDEX        78
Objectives

 Apply your new knowledge to solve
electrical challenges.
 Revise your knowledge of parallel and
series.

• The study guide suggests ways you could record in your exercise book.

Tuesday, 27 March 2012                         INDEX                        79
Challenge 1

An easy one to start with. There are three lights in a kitchen.
Design and make a circuit where they all come on with one
switch.

1. Remove one bulb from its holder. Do the other two stay on?
(They should do!)
2. Draw the circuit as a standard circuit diagram. Add a caption to
explain the function of the circuit.
3. Measure the current with an ammeter. Does the current change
if one bulb is removed? Add a caption to explain this part.
PHOTOGRAPHS

Tuesday, 27 March 2012                       INDEX                     80
Challenge 2
There are three lamps in a shed. Design and
build a circuit that allows each lamp to be
switched on and off separately.

1. Draw the circuit as a standard circuit diagram.
Add a caption to explain the function of the
circuit.
2. Measure and record the current with one, two
and three bulbs switched on. Record your
results and explain any changes.
PHOTOGRAPHS

Tuesday, 27 March 2012           INDEX                81
Challenge 3
Charles Slime, the well known ‘smoothy’ likes to have ‘mood’
lighting in his sumptuous living room. Design and build the
circuit so that he can dim his table lamp.

1. Draw the circuit as a standard circuit diagram. Add a caption to
explain the function of the circuit.
2. Measure the voltage across the bulb as the potentiometer is
3. Measure the voltage across the potentiometer as it is turned.
4. Finally, measure the voltage across the bulb and potentiometer
together as the potentiometer is turned. Record your observation.
5. Conclude your findings for parts 2, 3 and 4 above.

PHOTOGRAPHS

Tuesday, 27 March 2012                      INDEX                       82
Challenge 4
When Sophie goes camping she discovers that the
battery in her home-made lamp doesn’t last long.
To try to solve the problem she adds a second
battery cell. Now the bulb keeps blowing.

1. Draw Sophie’s home-made circuit as a standard circuit
diagram, first with one battery cell, then with two.
she is doing wrong.
3. Draw a standard circuit diagram to show how she
could have connected the second cell to make the
bulb stay alight for longer without blowing it.
PHOTOGRAPHS

Tuesday, 27 March 2012              INDEX               83
Round ups

Scores out of 5…
 We were able to apply your new
knowledge to solve electrical challenges.
 We think we’ve got the idea of parallel
and series.

This is the end of this study unit.

Tuesday, 27 March 2012      INDEX              84
Lesson 8

Finishing off

Tuesday, 27 March 2012   85
Equipment

 Whiteboards, pens & erasers.
 KS3 Levels 4 to 5 booklets.
 ‘How am I doing?’ sheets.

Tuesday, 27 March 2012    INDEX   86
Objectives

 To help complete your learning.
 To establish what level you are working at.
 To establish what things you are doing well.
 To decide on some targets.

Tuesday, 27 March 2012          INDEX             87
Bookwork check list
1.    Lesson 1: How much do you know?

2.    Homework task 1: Complete all the key questions. ‘HOW MUCH DO YOU KNOW?’

3.    Lesson 2: Connecting basic circuits

4.    Lesson 3: Electric current

5.    Homework task 2: Complete the two graphs. Trim and fix them into your book.

6.    Lesson 4: What do your results show? What if we used a different type of circuit?

7.    Lesson 5: Series & Parallel. Dealing with the results. Where to put the ammeter.

8.    Lesson 6: Resistance

9.    Homework task 3: Draw a graph of length of wire against current.

10.   Lesson 7: Applying your knowledge to electrical challenges

Tuesday, 27 March 2012                                          INDEX                      88
What are you doing well?

You can help each other to
do this.

Make a list of two or three things that your teacher
says you are doing well.

Tuesday, 27 March 2012             INDEX                89

book.
What things does the
Work in pairs           teacher want improved?
Choose two things and
write them on the
Now redraft the targets   whiteboard.
sheet.

Tuesday, 27 March 2012       INDEX                90
Lesson 9: Assessment

Prepare for exams.
Get experience of the types of questions.
Learn how to work at pace.

Tuesday, 27 March 2012                              91

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