Download Secondary Genecon Hand Generator Teachers Notes

Genecon® Teaching notes
How to use Genecon V3 / DUE ........................................................................................................................2
Precautions.......................................................................................................................................................3
Teaching ideas and activities.
1. Using a Genecon as an alternative power supply............................................................................................4
Using a data logger and Voltage sensor...........................................................................................................5
2. Demonstrating the efficiency of electrical devices....................................................................................6
3. What happens as you add more lamps to a circuit? .....................................................................................8
Using a data logger and Voltage sensor...........................................................................................................9
4. Adding more lamps to a circuit and testing energy used by how a second generator rotates ........ 10
5. Charging a capacitor.......................................................................................................................................... 12
A simple charge and discharge of a Capacitor............................................................................................. 13
Controlling the electric flow by using a diode ............................................................................................. 14
Using a data logger and Voltage sensor......................................................................................................... 15
Using stored energy........................................................................................................................................... 16
Which way does the electricity flow on charge and discharge? ............................................................. 18
What happens to the direction of handle turn when charging and discharging a capacitor? .......... 18
6. Electromagnetism ............................................................................................................................................. 22
7. Studying electromagnets ................................................................................................................................ 24
Using a data logger and Magnetic Field sensor .......................................................................................... 26
8. Making and testing your own electromagnets ............................................................................................ 27
9. Converting movement energy to electricity then to heat ....................................................................... 29
a. Using a glass thermometer ......................................................................................................................... 29
b. Using a data logger with a Temperature sensor .................................................................................... 30
c. Using resistors and LCD thermometer..................................................................................................... 32
Data Harvest 2012 DO 242 issue 1
1
Genecon® Teaching notes
How to use Genecon V3 / DUE
The Genecon electricity generators are for educational use. Polarity and voltage will depend upon
speed and direction of winding. When powered by another Genecon or low voltage power source, it
becomes a motor.
There are two versions of the
Genecon
The Genecon V3 identified
by green plastics. Produces a
nominal voltage of 3 V – fast
and furious winding will
produce up to 6 V.
The Genecon DUE identified
by pink plastics. Produces a nominal voltage
of 6 V – fast and furious winding will produce
up to 14 V.
Both versions come with output leads fitted with
sheathed crocodile clip terminals
Note: With both generators, voltage output is regulated by the speed of handle turning. The gearing makes a gentle
comfortable turn produce the nominal voltage. The capacity to produce an over voltage by fast winding should be
considered when deciding which Genecon generator to use and the rating of the electrical components to use with it.
You will feel a slight click when the cable connector is securely positioned. The lead sets are keyed for use
with the V3 or DUE.
Connector for Lead
Winding Handle
With the red lead at the top, clockwise winding will create a positive (+ve) voltage on the red lead. Winding
clockwise will create a negative (-ve) voltage on the red lead.
For left-handed users the connector can be reversed, black lead to the top. This will give a negative (+ve)
voltage on the red with an anticlockwise wind. This gives a more natural winding action for left-handed
users.
Connect the crocodile clip to the experiment device. Hold the Genecon in one hand and turn the handle to
generate electricity.
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Genecon® Teaching notes
Precautions
•
Be careful of electrical shock. Genecon generators connected in series can generate a high voltage,
posing the possibility of electrical shock. Using the units in parallel will increase the current. Unlike a
chemical cell, the output is dependant on how fast the generator can be turned not the capacity of the
unit.
•
Do not connect multiple Genecon generators to a capacitor. Always check electrolytic capacitors,
reversed polarity or over voltage can permanently damage a capacitor and potentially burst the
capacitor. The electrolyte from a burst capacitor should be considered as harmful and skin contact will
require treatment.
•
The Genecon teaches the relationships between energy, power and electricity. The voltage output is
only regulated by the winding speed. Do not use this generator as a battery or charger replacement e.g.
for charging a cell phone, MP3 player, PDA, digital camera or any other devices. Data Harvest cannot be
liable for damages from misuse of the generator or from applying voltage to a device above its capacity.
•
Fast turning the handle in the short circuit condition e.g. cables
connected together may damage the product.
•
The polarity of the Genecon depends on the winding direction. Check
when connecting to component that has polarity such as an LED,
buzzer, or capacitor.
•
The generator’s gears are made of a durable plastic, but can be
damaged if too much force is used during winding. A replacement gear
set is available.
•
Do not expose the Genecon to high temperature, flames or solvents.
•
Do not spill water on or immerse the Genecon in water.
•
Do not store the Genecon in high temperatures or humidity.
•
Do not drop the Genecon. The impact may damage the product.
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Genecon® Teaching notes
Using a Genecon as a power supply.
Suitable for a V3 or DUE generator
You will need
•
A Genecon and connecting lead.
•
A small lamp and holder. (3 to 6 V for the V3 Genecon or 6 to 12 V for the DUE).
•
An LED with a protecting resistor (typically 300 Ohms for a 3.5 V LED).
•
A d.c. motor (3 to 6 V for the V3 Genecon or 6 to 12 V for the DUE).
•
A small battery operated car or model.
You may find you need to add wires to some components to allow the crocodile clips to make
contact.
What to do
Disconnect the device from any power source, and use the Genecon, to investigate the cause and
effect between Genecon activity, and the activity of the connected device.
This activity shows the relationship between physical work and electrical work.
Questions to ask
1.
Where does the energy come from as you wind the Genecon?
2. What happens if you wind the Genecon slowly, more quickly?
3. Where is the energy in a battery? Why does it run out?
Some background information:
Work is the use of energy. Winding the hand generator is work; you are using energy to create activity to
turn the handle.
Energy is the potential or capacity for work.
Power is the rate at which work is performed or energy is converted.
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Genecon® Teaching notes
Using Genecon and a Voltage sensor
You will need
•
A Genecon with output leads.
•
Electrical component e.g. a bulb. The components need to connect to the crocodile clips on
the Genecon’s output lead.
•
A ±12 or 20 V Voltage sensor connected to a data logger.
What to do
•
Use the data logger and voltage sensor to explore how voltage changes with;
o
Speed of winding.
o
Direction of winding.
Genecon 3V with 3.5 V lamp.
(Sensor axis limits altered to display ±6 V)
5
Genecon® Teaching notes
Demonstrating the efficiency of electrical devices.
In this experiment, two Genecons of the same type are connected together.
The Genecon whose handle is turned will be the generator; it will be used to drive the motor of the
second Genecon.
By comparing how much energy we put in to the system and how much comes out, we can calculate the
efficiency of the system. The process is simple, count the number of turns of the generator and count
the number of turns of the motor. Any differences must be due to energy loss. Use the exercise to
get students thinking about energy transfers and energy loss in system.
You will need
Two Genecons of the same type with their output leads.
What to do
•
Connect the crocodile clips of the Genecons together, matching colours.
•
Ask two students to hold a Genecon each.
ƒ
Student A - turns and counts how many times they turn the handle.
ƒ
Student B – counts the number of handle turns.
They will need a fixed reference point to count against - the label on the top of the Genecon is
probably the best option. Make sure the handles can turn without tangling in anything.
•
Wind the handle of the generator unit 10 times and count how many times the motor turns.
Questions to ask.
1.
To practice some maths, find the ratio of generator (A) turns to motor (B) turns expressed as
a percentage.
Test
Turns of
generator (A)
1
10
2
10
3
10
Turns of
motor (B)
% Efficiency
(Turns of generator/ Turns of motor) x 100
2. Why are the number of turns not equally matched?
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Genecon® Teaching notes
3. What is creating the loss of turns between the two Genecons - you should be able to come with
at least three explanations. (Hint: listen carefully, watch, and feel what you are doing!).
4. What happens to the calculated efficiency if you increase the generator turns to 100? Explain!
Additional activities.
1.
Try comparing the efficiency with
•
A slow handle turn.
•
A quick handle turn.
•
The Genecons positioned upright.
•
The Genecons positioned sideways.
2. Does the speed of turning have any effect?
3. Does it matter who winds and who counts?
4. What if you made the connecting wires longer?
Extension
1.
Connect a resistor between the two Genecon. Keeping the ten turns of the generator (A), how
does the number of turns of the motor (B) change?
2. Could you predict the number of turns of the motor (B) with different resistors?
3. Could you count the number of turns of the motor (B) and work out the value of a resistor?
7
Genecon® Teaching notes
What happens as you add more lamps to a circuit?
You will need
•
Genecon with output lead
•
A parallel circuit made up
with at least three lamps.
The lamps must be able to
be turned on and off.
The voltage rating of the
lamps will depend on the
Genecon being used (3 to 6V
for the V3 Genecon or 6 to
12V for the DUE).
What to do
•
Connect the Genecon to the parallel lamp circuit. It does not matter which way the connections
are made; the lamps will work with either direction of winding.
•
Start with no lamps turned on.
Note: You can turn lamps on and off by unscrewing them in the holder. Unscrew only enough to stop them
lighting up.
•
Wind the Genecon handle at a constant speed and feel the effort required to turn the
Genecon.
•
While still winding the handle turn on the first lamp. How has the effort to turn the Genecon
changed? Note the brightness of the lamp and how easy it is to make it bright (take care the
lamp is not blown by over eager Genecon action!).
•
Repeat for each additional lamp in the circuit.
Questions to ask.
1.
What happens as more lamps are turned on?
2. Can you feel the effort to wind the handle change as you turn lamps on.
3. Does it matter which lamps are turned on or off?
4. Does the order of turning the lamps on and off matter?
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Genecon® Teaching notes
What happens as you add more lamps to a circuit? Using a data
logger and Voltage sensor
You will need
•
A V3 or DUE Genecon with output leads.
•
A parallel circuit made up with at least three lamps. The lamps must be able to be turned on
and off.
Note: You can turn lamps on and off by unscrewing them in the holder. Unscrew only enough to stop them
lighting up.
•
The voltage rating of the lamps will depend on the Genecon being used (3 to 6 V for the V3
Genecon or 6 to 12 V for the DUE).
•
A ±12 or 20 V Voltage sensor connected to a data logger.
What to do
•
Connect the Genecon and Voltage sensor to the parallel lamp circuit.
•
Open the EasySense software and select EasyLog (record until you stop it).
•
Start with no lamps turned on. Start logging; wind the Genecon handle at a constant speed.
Feel and note the effort required to turn the Genecon.
•
While still winding turn on one lamp. Note how the effort to turn the Genecon handle has
changed. How bright is the lamp?
•
Turn on a second lamp; again note the effort to turn the Genecon handle and the brightness of
the lamps. Repeat for each additional lamp in the circuit. Stop logging.
Why don’t we get a nice smooth graph line? Why does it go up and down all the time?
9
Genecon® Teaching notes
Adding more lamps to a circuit, using a second Genecon to measure
energy use.
Connect a second Genecon to the circuit and you can see how much energy has been used to light the
lamps. One Genecon is the generator (A) and one becomes the motor (B).
A - generator
B - motor
You will need
•
Two Genecons of the same type with their output leads.
•
A parallel circuit made up with at least three lamps. The lamps must be able to be turned on
and off, and there should be the ability to connect two Genecons to the circuit.
The voltage rating of the lamps will depend on the Genecon being used (3 to 6 V for the V3
Genecon or 6 to 12 V for the DUE).
The diagram shows the Genecons in use with a Lamp Load kit.
What to do
•
Connect the Genecons to the parallel lamp circuit. It does not matter which way the
connections are made.
•
Start with no lamp turned on.
•
Wind the generator (A) handle at a constant speed for 10 turns and count the number of turns
of the motor (B).
•
Turn on the first lamp and repeat.
•
Turn on the second lamp and repeat. Continue until all lamps in the circuit are turned on.
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Genecon® Teaching notes
Number of lamps
connected
How did the
Genecon feel to
turn?
Lamp
brightness level
Number of turns
of the generator
0
10
1
10
2
10
3
10
Number of turns
of the motor
The students should notice that as each lamp is turned on it becomes harder and harder to turn the
handle of the generator. They should also notice that faster handle turning improves the brightness of
the lamps.
The number of turns of the motor will decrease for every extra lamp.
Use generator turns / motor turns to work out a turns ratio.
Plot a graph of the turns ratio vs. no lamps. Use a best fit to predict what would happen for extra
lamps or for 25 turns of the generator.
What difference does the speed of the generator (A) have?
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Genecon® Teaching notes
Charging a capacitor
Suitable for a V3 Genecon
Caution: Capacitors store energy; it is possible to build up significant charge (energy store) on a capacitor. It
is best to use recommended values e.g. a 1F 2.3 V or a 10F, 2.5 V capacitor.
Precautions:
Electrolytic capacitors should only be charged to the indicated voltage. Wrong polarity or overcharging can
burst the capacitor.
If you are using a component capacitor, use a diode in series with the +ve feed from the generator. The
diode controls the flow of electricity and the voltage drop across it will reduce the potential to overcharge the
capacitor. We recommend using a 1N4001 diode.
Before starting the work, it would be good idea to consider with the students what a capacitor is and how it
works. A quick description of the labels on the capacitor is advised to educate about the working voltage,
charge stored and basic safety rules. There is a real risk of damaging or bursting the capacitor if it is reverse
charged. The energy stored can be high, and a routine of discharging before handling is not a bad idea. It
has been known for capacitors to charge from static in the environment.
The purposes of the experiments are,
1. To show storage of electricity.
2. To make a comparison between the store of electricity on a capacitor against a chemical cell.
3. As a stimulus / introduction to capacitor work.
4. To consider Fleming’s right and left hand rules.
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Genecon® Teaching notes
Charging and discharging a Capacitor
Suitable for a V3 generator
You will need
•
V3 Genecon and lead set – make sure the direction of rotation for +ve and –ve voltage is clearly
understood and identified.
Note: If the red lead inside the lead connector is at the top, winding the handle clockwise gives a
positive (+ve) voltage at the red lead
•
Minimum of a 1F capacitor (make sure + and – are clearly identified).
What to do
•
Connect the generator to the capacitor,
using the crocodile clips. Check the
polarity before starting work.
•
Wind the Genecon, quite fast, for about
30 turns to charge the capacitor.
•
Let go of handle. Even with relatively
few winds, you should get enough store
of electricity to make the Genecon
motor continue to turn the handle.
Extensions
•
Compare the number of charge turns with the number discharge turns.
•
Feel the resistance change as you charge the capacitor (moving electrons = work).
•
How does the speed of turn affect how charge is stored?
•
How does the handle rotate relative to the Genecon during charge and discharge? What makes
the difference?
13
Genecon® Teaching notes
Controlling the electric flow by using a diode
Suitable for a V3 generator
Control of the direction of electric flow is important when using things like wind turbines or solar cells
that are storing electricity during periods of resource activity for use at periods of resource
inactivity. You will have noticed, in the previous exercise, that if you let go of the handle, the stored
charge drives the motor. This isn’t what is really required; we need to control the flow of electricity to
and from the energy store.
You will need
•
V3 Genecon lead set – make sure the direction of rotation for +ve and –ve voltage are clearly
identified.
Note: If red lead inside the lead connector is at the top, winding the handle clockwise will create a
positive (+ve) voltage at the red lead
•
1F 2.3V capacitor (make sure + and – are clearly identified).
•
A 1N4001 diode
•
Crocodile clips and patch leads.
What to do
•
Connect the red crocodile clip (+ve) of the Genecon to the unbanded end of the 1N4001 diode.
•
Connect the other leg of the 1N4001 diode to the +ve of the capacitor.
•
Wind the handle slowly for about 10 turns to charge the capacitor.
•
Let go of the generator’s handle.
Questions to ask
1.
What difference does the diode make?
2. Does the generator’s handle still turn when you stop winding?
3. How can you explain the different behaviour to experiment 5.1?
14
Genecon® Teaching notes
Charging and discharging capacitors with data logger and Voltage sensor.
You will need
•
V3 Genecon generator and lead set – make sure the direction of rotation for +ve and –ve
voltage are clearly identified.
Note: With the red lead the top of the connector winding the handle clockwise will create a positive (+ve)
voltage at the red lead
•
1F 2.3V capacitor (make sure + and – are clearly identified).
•
A 1N4001 diode.
•
A ±12 or 20 V Voltage sensor connected to a data logger.
•
Crocodile clips and patch leads.
What to do
A simple charge and discharge of a Capacitor
•
Connect the Genecon to the capacitor with the red clip (+ve) to the +ve leg of capacitor.
Connect the Voltage sensor across the capacitor.
•
Open the EasySense software and select EasyLog. Start logging.
•
Wind the handle quite fast for about 20 - 30 turns to charge the capacitor. Let go of the
Genecon’s handle.
•
Stop logging when the capacitor is fully discharged (voltage near zero).
Controlling the electric flow by using a diode
•
Connect the red crocodile clip (+ve) of the Generator to the unbanded end of the diode and the
other end of the diode to the +ve leg of the capacitor
•
Select Overlay and start logging.
•
Wind the handle quite fast for about 20 - 30 turns to charge the capacitor. Let go of
generator’s handle.
•
Stop logging.
Results using Genecon V3 (Y - axis altered to 0 – 1.30 V)
15
Genecon® Teaching notes
Using stored energy
Suitable for a V3 generator
In activity 5.1 you may have noticed that initially the Genecon takes effort to turn, but as the
capacitor charges up the effort decreases. If a diode is not being used you will not notice this. At the
point the capacitor is nearly fully charged the handle is easy to turn and may start to ‘run away’ from
you. However much charge you put on the capacitor the significant thing is that it took time, effort
and involved work. How long does all that work you put into charging the capacitor last?
In this experiment, charge the capacitor to the same level and then connect a variety of electrical
devices to the capacitor to see how long they do what they are supposed to do!
Red lead
+
Capacitor
Resistive load e.g. lamp
Black lead
Step 1: Charge the capacitor
Step 2: Let the capacitor discharge
You will need
•
V3 Genecon generator and lead set – make sure the direction of rotation for +ve and –ve
voltage are clearly identified.
Note: With the red lead at the top of the connector winding, the handle clockwise will create a positive
(+ve) voltage at the red lead
•
1F 2.3V capacitor (make sure + and – are clearly identified).
•
Electrical component e.g. a torch lamp (3 V) or an LED (with protecting resistor) or very small
low voltage d.c. motor (2 to 3 V).
•
Timing clock (you may be able to use a data logger to measure the light output over time).
What to do
•
Connect the Genecon to the capacitor, the red crocodile clip (+ve) should connect to the +ve leg
of the capacitor.
•
Wind the handle to charge the capacitor, keep winding until the handle becomes very easy to
turn.
•
Disconnect the Genecon, try to be quick.
•
Connect an electrical component to the capacitor and start a timing clock. Let the component
run until it stops working.
Note: For some devices this may be difficult to work out, you will have to make a rule up to determine
when it stops. For example, torch lamps get dimmer and dimmer and then you suddenly realise they are
not alight any more. Motors however stop moving! Perhaps an opportunity to do some data logging?
16
Genecon® Teaching notes
Questions to ask
1.
Which device gave the longest work period for the charge?
2. Which device do you think was worth the time and effort to store the charge and let it
work?
3. Consider the effort you had to put into this activity, how much of your work was ‘wasted’ –
didn’t seem to do anything?
4. Work in to work out is measure of the efficiency of the device, which one was the most
efficient?
5. It took you time to make and store the electricity, time is money! Why do you want to spend
money on work that does nothing for you? Think about this next time you leave a light on,
use a hairdryer, leave the television on in an empty room – somewhere work has been done to
keep that device operating, work you have to pay for with money, emissions, pollution, etc.
Is it worth it?
17
Genecon® Teaching notes
Which way does the electricity flow on charge and discharge?
Suitable for a V3 Genecon
You may have noticed something that you thought was unusual when you charged the capacitor and left
the Genecon connected as you discharged it. The Genecon when acting as a motor turned the same
direction as when it was acting as generator. Shouldn’t the generator turn the opposite way when
acting as motor? The experiment has two steps, one to make a simple direction of electricity flow
meter and then to watch what happens on charge and discharge of the capacitor.
Occasionally, a compass needle may ‘stick’ and not return to its original position. The culprit is residual
magnetism, and the problem can be corrected by momentarily reversing the current.
Teacher’s note: The Genecon is effectively going to be used short circuited in this investigation. Make sure the
students only rotate the Genecon handle slowly and for short periods. Fast winding or long periods can potentially
damage the generator / motor.
You will need
•
A small direction compass (plotting compass).
•
V3 Genecon and lead set
Note: With the red lead at the top of the connector, winding the handle clockwise will create a positive
(+ve) voltage at the red lead
•
1F 2.3V capacitor (make sure + and – are clearly identified).
•
5 to 6 cm long piece of stiff insulated copper wire, insulation removed at each end to allow
connection.
•
Some tape (masking tape), plasticine or Blu - Tack to hold things in place as you do the work.
Making a direction of flow meter
•
Place the direction compass on the bench
and place the wire underneath it, move them
around until the pointer runs parallel to the wire.
You may need small pieces of modelling clay to
support the compass above the wire.
•
Connect the Genecons’ to the wire. Make a note
of which end of the wire is connected to the red
crocodile clip; you will want to connect your
capacitor up the same way.
•
Use a piece of tape to fix the wire to the bench.
•
Wind the Genecon clockwise for a short period.
Watch the compass needle.
1.
What happens to the needle in the compass?
2. How would you describe what happens?
•
Wind the Genecon anti-clockwise gently for a short period.
1.
What happens to the needle in the compass?
2. How would you describe what happens?
•
Repeat several times until you are convinced about the pattern you see.
18
Genecon® Teaching notes
Testing the charge and discharge
Now you have seen a way of finding the direction of
flow of electricity in the circuit,
•
Connect the capacitor between the generator and
the wire taped to the bench. Make sure the red
lead from the Genecon is going to the +ve leg of the
capacitor.
•
Wind the Genecon to charge the capacitor and
watch the compass needle.
1.
What happens to the compass needle?
2. Describe its position and motion.
•
Stop winding and let the capacitor discharge
(through letting the Genecon turn).
1.
What happens to the compass needle?
2. Describe its position.
Questions to ask
1.
How did the compass needle change its direction when the capacitor was being charged?
2. How did the compass needle change its direction when the capacitor was being discharged?
3. Which direction did the Genecon handle turn when the capacitor was charging and discharging
4. In part 1, what did the change in compass direction tell you about the flow direction of the
electricity?
5. What direction did the electricity flow into the capacitor? And which way did it flow out. Use
the information from the activity to explain and justify your answer.
19
Genecon® Teaching notes
What happens to the direction of handle turn when charging and
discharging a capacitor?
You have evidence that current flow changes direction on charge and discharge, but the handle on the
Genecon turns in the same direction on charging and discharging.
Wind the Genecon to charge the capacitor, and let the capacitor discharge through the Genecon,
observe the turning handle.
1.
What direction does the handle turn on charge and discharge?
2. What direction does the current flow (as seen on your simple flow meter) on charge and
discharge?
3. Why does the turning handle behave like it does? Can you explain why it turns in the direction
it does on discharge?
The practical is simple, explaining what you see is more complex and is the heart of this part of the
work. You will get answers ranging from “it just does” to correct or nearly correct solutions; the point
is that answers have to be supported by the evidence presented.
We would expect very different answers from different aged group students. Younger students may
think it is to do with the gears. Students who have done higher-level physics should make the
connection to the right and left hand laws and how forces and magnetism interact. An advanced answer
is provided below,
Fleming’s left hand and right hand rules
When the capacitor is charged the Genecon generates current due to a coil moving in a magnetic field.
When the handle stops turning, the capacitor discharges by a current in the opposite direction to the current
that charged it. This current interacts with the magnetic field of the Genecon to create a force on the coils in
the same direction as the original handle turning motion.
Using Flemings hand rules,
Hold both hands out in front of you to show Flemings motor and generator rules. You will see that the second
fingers (the current direction) on each hand point in opposing directions (towards each other).
20
Genecon® Teaching notes
The motion direction (the thumb) is unaltered; therefore, the direction of motion in the generator and motor is
the same. The trick is in identifying the rotating core of the motor as the conductor.
Fleming's left hand rule (for electric motors) shows the direction of the thrust on a conductor carrying a
current in a magnetic field. The left hand is held with the thumb; index finger and middle finger at right angles
(refer to diagram above).
•
•
•
The First finger represents the direction of the magnetic Field. (north to south)
The Second finger represents the direction of the Current (the direction of the current is the direction
of conventional current; from positive to negative).
The Thumb represents the direction of the Thrust or resultant Motion.
Fleming's right hand rule (for generators or dynamos) shows the direction of induced current when a
conductor moves in a magnetic field. The right hand is held with the thumb; first finger and second finger at
right angles to each other (refer to diagram above).
•
•
•
The Thumb represents the direction of Motion of the conductor.
The First finger represents the direction of the Field. (north to south)
The Second finger represents the direction of the induced or generated Current (the direction of the
induced current will be the direction of conventional current; from positive to negative).
21
Genecon® Teaching notes
Experiments with electromagnetism
When a current flows along a wire, it creates a magnetic field at right angles to the direction of the flow of
electricity. In this section a few experiments with electromagnetism and electromagnets will be conducted.
As an introductory activity you can show how a direction compass is affected by magnetism using a simple
bar magnet. The South pole of the magnet is attracted to the North pole on the compass pointer; this may
start a discussion on how the magnetic field is changing when they see the effect of the current in a
conductor.
Electromagnetism
Suitable for V3 and DUE.
If a conductor wire is placed near to a magnetic direction compass then any change in the magnetic
field surrounding the compass will make the compass needle move.
Teacher’s note: The Genecon is effectively going to be used short circuited in this work. Make sure
the students only rotate the Genecon handle slowly and for short periods. Fast winding or long periods
of use can damage the generator / motor.
You will need
•
A small direction compass (plotting compass).
•
V3 or DUE Genecon generator and lead set – make sure the direction of rotation for +ve and –
ve voltage are clearly identified.
Note: With the red lead at the top of the connector, winding the handle clockwise will create a positive
(+vet) voltage at the red lead
•
A length of solid-core lightly insulated copper wire, long enough to make 3 turns around the
circumference of the compass. Make sure the wire ends have the insulation removed so the
generator lead can be connected
•
Some tape, plasticine or Blu-Tack to hold things in place as you do the work.
What to do
•
Place the coil you have made around the compass (try to make the coil go West East). Place the
compass with coil on the bench and move it around until north on the scale and the needle point
in the same direction. You may need plasticine or Blu-Tack to hold it in place.
22
Genecon® Teaching notes
•
Connect the Genecon to the coil. Make a note of which end is connected to the red crocodile
clip.
•
Wind the Genecon clockwise gently for a short period.
1.
What happens to the compass needle?
2. How would you describe what happens?
•
Wind the Genecon anti clockwise gently for a short period.
1.
What happens to the needle in the compass?
2. How would you describe what happens?
Wrap the wire in a coil around the compass (over the top and under the base). Turn the compass until
the compass needle is parallel with the wire loops. Repeat.
•
•
•
•
What happens to the compass needle?
How would you describe what happens?
Investigate changing the position of the coil, does it make any difference?
Does the amount of deflection depend on the rate at which you rotate the handle?
23
Genecon® Teaching notes
Investigating electromagnets.
Suitable for V3 and DUE generators
The electromagnet is a coil, of a number of turns of conducting wire, with a core of soft, strongly
ferromagnetic material (usually soft iron). It’s a magnet that is only magnetised while a current is
passing through the coil. The reason why it should be soft iron is an investigation of its own, as is why
the coil needs a core at all.
For simplicity, we suggest you use pre-wound coils. In a later investigation, the students will make their
own electromagnets. Pre-wound coils make a good comparative standard for the students own make(s).
You need at least two students for the work. Trying to pick up paper clips with the electromagnet and
winding the Genecon is very difficult for a solitary investigator!
Teacher’s note: ‘Soft’ iron and ‘Hard’ iron are not physical descriptions of the iron; they refer to the
ability of the iron to retain magnetism after the iron has been removed from any magnetic influence.
Soft iron loses its magnetism almost immediately, hard iron retains its magnetism (not always as strong,
but it remains).
Be cautious of how you describe magnetic materials - iron is a magnetic material but it is not the only
one. Many of the modern super magnets have no iron at all in them and copper is affected by
magnetism but is not magnetic!
You will need
•
V3 or DUE Genecon generator and lead set.
•
A pre wound electromagnet preferably with a removable soft iron core e.g. the Genecon
B10­2631­05 Coil.
•
Small pile of paper clips
Additional equipment.
•
For questions to explore: 2 bar magnets
•
Extension equipment: Pencil, iron nail, aluminium foil
What to do
•
Connect the terminals of the electromagnet to the Genecon. Make a note of which is the
positive and which is the negative connection (you will need this to make a comparison).
•
Place the iron core into the magnet coil; it should be positioned equally in and out of the coil.
•
Place a small pile of paper clips on the bench.
24
Genecon® Teaching notes
•
Wind the handle of the Genecon clockwise and try to pick up the paper clips.
1.
How many can you pick up?
2. What happens to the paper clips (number of paper clips) attached to the iron core when
you stop winding?
•
Detach any paper clips that may remain attached and return to the pile on the bench.
•
Wind the Genecon in the anti clockwise direction and try to pick up the paper clips.
1.
Has the direction of winding made any difference to the number of paper clips you can lift?
2. What happens if you wind the Genecon in the opposite direction while the clips are still
attached?
Questions to explore
When you have bar magnet it has a mark on one end or different colour each end to identify the North
and South pole of the magnet.
1.
What happens if you place N to S, S to S and N to N?
2. What happens if you wind the Genecon clockwise and hold the N pole of a bar magnet near
to the electromagnet?
3. What happens if you wind the Genecon anti clockwise and hold the N pole of a bar magnet
near to the electromagnet?
4. What does this tell you about the direction of winding and the magnetic pole created on the
electromagnet?
Extension
1.
What happens if you remove the iron core and just use the coil?
2. What happens if you replace the iron core with a pencil?
3. What happens if you replace the iron core with an iron nail or a piece of rolled up aluminium
foil?
25
Genecon® Teaching notes
Investigating electromagnets, with a data logger and Magnetic Field
sensor
If you have a data logger and a Magnetic field sensor, measure the real strength of the
electromagnet. Remember to keep the distance between the sensor and the electromagnet constant or
the results will not be fair test.
You will need
•
V3 or DUE Genecon generator and lead set.
•
A pre wound electromagnet preferably with soft iron core
•
A ±10 mT Magnetic Field sensor set to the Axial range and a data logger.
What to do
•
Connect the Magnetic Field sensor to the data logger.
•
Connect the terminals of the electromagnet to the Genecon. Make a note of which is the
positive and which is the negative connection (you will need this to make a comparison).
•
Place the iron core into the magnet coil; it should be positioned equally in and out of the coil.
•
Position the Magnetic Field sensor end-facing to the coil. Secure in position using some
plasticine or Bu-tack.
•
Open the EasySense software and select EasyLog (record until you stop it). Start logging.
•
Wind the handle of the generator clock wise, stop then wind anticlockwise, stop. Stop logging.
Axial Field (mT)
Questions
1.
What happens when you
wound the Genecon
clockwise?
2. What happens when you
wound it anti clockwise?
3. What does this tell you
about the direction of
winding and the magnetic
pole created on the
electromagnet?
4.00
3.00
2.00
1.00
0.00
0
03.25
06.50
-1.00
-2.00
-3.00
-4.00
23 March 2011 10:59:43
26
Time (ss)
09.75
13.00
Genecon® Teaching notes
Making and testing your own electromagnets
Suitable for V3 and DUE generators
You can make electromagnets and use power supplies and dry cells to power them. The disadvantage is
that the coil of wire which makes the electromagnet is effectively a short circuit across the power supply. It
is easy to overload the supply and potentially damage the coil. The physical generation of electricity by a
hand generator goes a long way to reducing the problems. A low value resistor is a useful protection in the
circuit, but may need explaining.
Six inch nails make good formers to wind the coils onto; the flattened head of the nail makes a good end
stop for the coil. Be careful, some bolts and nails are made of stainless steel - this does not magnetise.
You need at least 2 people for the work. Holding the electromagnet and winding the Genecon or holding the
coils when adding the tape is very difficult for the solitary investigator!
You will need
•
V3 or DUE Genecon generator and lead set.
•
Pile of paper clips
•
Equipment for students to make their own electromagnets:
•
A soft iron former to make the coils of the electromagnet e.g. a 150 mm large nail or bolt
or other piece of iron that can be wound with wire.
•
About 3 m of lacquered or thinly insulated solid core wire with about 2 cm of insulation
removed from either end.
•
Tape to secure the coils when made.
Extension equipment: A ±10 mT Magnetic Field sensor set to the Axial range and a data logger to give
a value to the magnetic fields generated.
What to do
•
Use the length of wire to make a set of at least 20 turns around the iron former. Try to get
the coils as close to each other as possible.
•
Use tape to lightly hold the coil together - make sure you do not cover the end of the wire that
will connect to the generator’s leads.
•
Connect the un-insulated ends of your coil to the generator.
•
Wind the handle of the generator clockwise and find how many paper clips you can pick up.
•
Detach any paper clips that may remain attached and return to the pile on the bench. Wind the
Genecon in the anti clockwise direction and find how many paper clips you can pick up.
Questions to explore
1.
What happens if you increase the number of turns you made?
2. What happens if you have space between the coils?
3. How hard do you have to wind the generator to make the magnet strong enough to pick up the
paper clips?
4. What makes the most difference, the number of coils, the speed you wind the generator or
the tightness of the coils?
27
Genecon® Teaching notes
Extension
If you have a data logger and a Magnetic field sensor, measure the real strength of the magnets you
make. Remember to keep the distance between the sensor and the electromagnet constant or the
results will not be a fair test.
28
Genecon® Teaching notes
Experiments of energy conversion
Converting movement energy to electricity then to heat
Suitable for V3 and DUE generators
The student investigator is the power behind the generator. The winding of the generator is very
intuitive for the development of concepts of energy, power, and work. Care needs to be taken to not
create confusion with non-scientific use of the words.
•
Energy is the capacity (potential) for work.
•
Work is the transfer of energy during over time.
•
Power is the energy transferred per unit of time (the rate of energy transfer).
It is common in non-scientific every day English for the terms to be used as synonyms for each other.
You will need
•
V3 or DUE Genecon generator and lead set.
•
Resistance wire (e.g. Nichrome).
•
a. Glass Thermometer or
b. Data logger, Temperature sensor, and thin insulating tape.
Using a glass thermometer
What to do
Take the length of the resistance wire and wrap it round the bulb
of the thermometer.
Connect the generator to each end of the resistance wire.
Make a note of the temperature on the thermometer.
Wind the generator (it does not matter which way) for 2 to 3
minutes.
Stop winding and wait 10 seconds, look at the temperature.
Questions to explore.
1.
What has happened to the temperature on the thermometer?
2. Where did the energy come from to make the temperature change?
3. Describe the energy changes at each process; describe where loss of energy may have taken
place. What is the unit of energy?
4. Repeat winding for longer, or faster. What makes the most difference the speed of winding or
the time taken winding?
29
Genecon® Teaching notes
Using a data logger with a Temperature sensor
Temperature sensors consist of a thermistor housed inside a steel tube. Nichrome wire has no
insulation, and will short out against the metal housing of the Temperature sensor. Place a one layer
of thin insulating tape around the metal housing of the Temperature sensor before you wrap it with
the Nichrome wire. If it is thicker than one layer, it will make it difficult for the heat to get
through to the Sensor.
What to
do
•
Place a one layer thick piece of thin insulating tape around the body of the Temperature
sensor.
•
Wrap the nichrome wire tightly around the Sensor. When you let go it will spring out slightly
but will not undo. If you think the coil you have made will fall off the Sensor, add a small piece
of tape to hold it in place.
•
Connect the Genecon to the ends of the resistance wire.
•
Connect the Temperature sensor to the data logger. Open the EasySense software and select
EasyLog.
•
Start logging and begin winding the Genecon. Try to keep a constant speed for 30 to 60
seconds.
•
Stop logging. Select Overlay and begin logging again, repeat winding the generator but this
time slightly faster. You can repeat the process several times, winding faster each time.
30
Genecon® Teaching notes
Temperature changes created by winding the Genecon at different speeds, using EasyLog for 30
seconds with Overlay selected.
Questions to ask
1.
How did the speed Temperature created by winding at different speeds with the Genecon V3
generator using EasyLog for 30 seconds with Overlay selected affect the temperature?
2. Use the gradient tool to find the rate of temperature rise for each winding speed?
31
Genecon® Teaching notes
Using thermopower indicator
Suitable for V3 and DUE generators
The Thermopower accessory for the Genecon is a set of resistors with a heat sensitive tape attached.
The tape shows the temperature. As the temperature of the resistor changes, it is shown by the
digital temperature reading of the tape.
It takes quite a lot of winding to get a temperature change. This is excellent at showing that heat
energy is not free! It might make a student think about the energy cost of staying warm and why
reducing, the temperature of a house by one or two degrees can save so much energy and money.
You will need
•
V3 or DUE Genecon generator and lead set.
•
A resistor with LCD thermometer attached. E.g. Genecon B10-2631-01 Resistance with a liquid
crystal thermometer or Lascells Thermopower kit.
What to do
•
Connect the generator to the resistor LCD thermometer block, check to make sure the
crocodile clips are making contact with the terminals.
•
Wind the generator and watch the change in temperature on the liquid crystal thermometer.
•
Time how long it takes to make the temperature rise by 2, 4 and 6 degrees or 5,10,15 degrees
(depending on the temperature graduations on the tape).
Genecon® Is the registered trademark of Narika Corporation of Japan
32
Genecon® Teaching notes
Genecon lesson cue cards.
How do I show the Genecon is making electricity?
How can I show that electricity is being made?
Use light bulbs to show electricity is being made.
Use a data logger and voltage sensor or light sensor to find out.
Exploring, numbers
What happens if I wind my Genecon at different speeds?
How does winding the Genecon change the amount of electricity being made?
Use light bulbs to see what happens as I change the speed of winding.
Use a data logger, Voltage sensor and light sensor to find out.
Fair test, measuring, numbers
33
Genecon® Teaching notes
What happens if I connect two Genecons together?
When I wind the handle of a Genecon, I make electricity. If I connect one
Genecon to another can the electricity make the other Genecon go round
(unwind)?
Count how many times you turn one Genecon to make the other turn the
same amount?
Does the speed you wind make a difference?
Exploring
What happens if I add more light bulbs to my circuit?
Electricity is energy, winding the Genecon uses energy, light bulbs use energy.
Can I feel that energy being made and used?
Use a set of light bulbs and switches to feel what happens as I switch
light bulbs on or off.
How do we know it takes more energy to light up more light bulbs?
Exploring
34
Genecon® Teaching notes
What difference does using a light bulb or an LED for light
make?
Connect a light bulb to a Genecon and wind the handle, how much light do you
get? Is it hard to turn the handle? Does it matter which way you turn the
handle?
Connect an LED and repeat, answer the same questions.
What does LED stand for?
Exploring
Can I make a wind up torch?
Connect a light bulb to a Genecon and wind the handle, how much light do you
get? Is it hard to turn the handle? Does it matter which way you turn the
handle?
What happens when I stop winding?.
What is better, winding for light or having battery that goes flat?
Where would a wind up torch be a better idea than a battery torch?
Exploring
35
Genecon® Teaching notes
Can you see how much energy a light bulb uses?
We know light bulbs use energy; can we measure how much by using two
Genecons?
Connect one Genecon to the light bulb set. Connect a second to the
other end of the light bulb set.
Wind the handle of one Genecon and count the number of times the
other goes round. Turn on the bulbs one at a time, how do things
change?
What does LED stand for?
Exploring
How much energy is needed to make heat? (1)
When we turn a heater on where does the heat come from?
Connect a Genecon to a thermopower strip, wind the handle.
How long to go up by a degree?
How much work to get to the highest temperature?
Which takes more work heat making or light making?
Exploring
36
Genecon® Teaching notes
How much energy is needed to make heat? (2)
When we turn a heater on where does the heat come from?
Use some nichrome wire, temperature sensor and a datalogger to investigate
how much work is needed to make heat.
How long to go up by a degree?
How much work to get to the highest temperature?
Which takes more work, heat making, or light making?
How would you measure the work?
Exploring
Electric current, flow, and magnetism
How does electricity change magnetism?
Use some electrical wire, plotting compass and a Genecon to investigate
how electricity can alter magnetism.
How does the direction winding change the compass pointer?
How does the speed of winding change the compass pointer?
Which takes more work, heat making, or light making?
How would you measure the work?
Exploring
37
Genecon® Teaching notes
Making and powering electromagnets
How does electricity make a magnet?
Use some electrical wire, iron nails, and a Genecon to investigate how
electricity can make a magnet.
How does the direction winding change the magnet?
How does the speed of winding change the strength of the magnet?
How strong can you make your electromagnet?
Exploring
Genecon® is the registered trademark of Narika Corporation of Japan
38