Experiment
for the Science Kit
Lehrerheft Description/Manual
zur Experimentierbox
Electric Circuits
Electric Circuits
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2
Electric Circuits
Science Kit
Electric Circuits
Order no. 31772
This Science Kit is recommended for students at the age of 8–9.
Contents
List of Components............................................................................................... 4
Storing diagram.................................................................................................... 5
1Special learning aims......................................................................................... 6
2.Experiments........................................................................................... 7
2.1
Electric current flows.............................................................................. 7
2.1.1 Batteries and bulbs................................................................................... 7
2.1.2 The glass of the bulb................................................................................ 7
2.1.3 Battery test.............................................................................................. 7
2.2
Electric circuits........................................................................................ 8
2.2.1 Simple circuit........................................................................................... 8
2.2.2 Series circuit............................................................................................. 8
2.2.3 Parallel circuit........................................................................................... 8
2.2.4 The switch in the circuit........................................................................... 9
2.2.5 Building our own switch........................................................................... 9
2.2.6 Assembling a vehicle with two headlights............................................... 10
2.2.7 The headlight-test.................................................................................. 11
2.2.8 Trembling through a rollercoaster.......................................................... 12
2.3
Conductivity of materials..................................................................... 12
2.3.1 Which materials conduct the electrical current?...................................... 12
2.4
Danger through electric current.......................................................... 13
2.4.1 Electric current from the socket.............................................................. 13
2.4.2 Caution! High voltage!........................................................................... 13
2.5
Electric current generates heat............................................................ 13
2.5.1 Electric current generates heat............................................................... 13
2.6
Electric current sets in motion............................................................. 14
2.6.1 The electromagnet................................................................................. 14
3.
Underlying principles........................................................................... 14
4.
Important information......................................................................... 15
3
Electric Circuits
List of components
Illustr. no. Qty. Description
Order no.
1
20 Bulbs, 3,5 Volts, 0,2 Ampere.......................................................... 13430
2
2 Crocodile clips with plugs.............................................................. 15781
3
15 Materials for conductivity examination
in plastic boxes (no. 12662) containing:........................................ 13561
4 1 Piece of porcelain........................................................................ 13650
5 1 Glass bead.................................................................................. 13677
6 1 Iron nail...................................................................................... 13685
7 1 Piece of string............................................................................. 13669
8 1 Aluminium rivet.......................................................................... 13626
9 1 Brass screw................................................................................. 13634
10 1 Wooden disc............................................................................... 12590
11 1 Carbon rod................................................................................. 13642
12 1 Stone.......................................................................................... 12565
13 1 Copper ring................................................................................ 13588
14 1 Rubber rod ................................................................................. 13600
15
2 Copper wires, supple, 1.5 mm dia., 430 mm long....................... 512703
16
1 Copper wire, half-hard, 2 mm dia., 200 mm long........................ 512704
17
15 Thermometers, –3 °C to +103 °C................................................... 12735
18
15 Batteries, square, 4,5 Volts............................................................. 13359
1 Set of spare parts (in plastic box, no. 43150), containing:
19 1 BluTack, adhesive bonding compound........................................ 15775
20 10 pins........................................................................................... 15773
21 20 paper clips................................................................................ 12549
22
1 Plastic base, grey, 120 x 90 mm with 2 terminals......................... 512701
23
1 Wooden board, 120 x 90 mm........................................................ 15771
24
15 Screwdrivers, insulated, 110 mm................................................... 13481
25
1 Construction set for vehicle with fischertechnik components.......... 15760
26
15 Nails, iron, 80 mm......................................................................... 13553
27
32 Terminal clips, 7 mm (in plastic box, no. 12727)............................ 13464
28
7 Spools, for keeping enamelled copper wire pieces
after experiment............................................................................ 13510
29
1 Spool of heating wire (20 m) with grey cotton insulation............... 13545
30
1 Spool of copper wire (60 m) with transparent enamel insulation.... 13537
31
1 Spool of copper wire (20 m) with red plastic insulation.................. 13529
32
15 Lever switches................................................................................ 13499
33 15Bulbholders.................................................................................... 13448
Enclosed printed material
–
1 Experiment Description/Manual “Electric Circuits”....................... 317726
–
1 Storing diagram “Electric Circuits”............................................. 3177236
4
Electric Circuits
Storing diagram
3-14
1
2
15+16
17
18
19-21
32
33
22+23
31
30
29
28
27 26
25
24
25
5
Electric Circuits
1.Special learning aims
1.1 Electric current flows
1.2 Electric circuits
1.3 Conductivity of materials
1.4 Danger through electric current
1.5 Electric current generates heat
1.6 Electric current sets in motion
Please note:
Check the copper wires before
con­necting them. The insulation at the wire ends must be
stripped off !
6
Electric Circuits
2.Experiments
2.1 Electric current flows
2.1.1 Batteries and bulbs
Experiment 1
Bulb and battery are joined conductively to form a closed circuit that lights
up the lamp. The bulb will only light up if its two terminals are simultaneously in contact each with one pole of the battery.
Materials:
1 Battery (18)
1 Bulb (1)
Fig. 1
2.1.2 The glass of the bulb
Experiment 2
A defective glass makes the bulb unserviceable. In order to demonstrate
this, the glass of a miniature bulb may be carefully crushed by the teacher,
avoiding the filament from being damaged. The lamp is then connected
to the battery. With a brief flash the filament is burnt through immediately.
For this reason the air in the glass of the bulb is always pumped dry and
filled with an inert gas (argon or krypton).
Materials:
1 Battery (18)
1 Bulb (1)
Fig. 2
2.1.3 Battery test
Experiment 3
Test several batteries and sequence them: with which battery will the bulb
light up brightest, with which batteries will it light up less.
Materials: Batteries (18)
Bulbs (1)
7
Electric Circuits
2.2 Electric curcuits
2.2.1 Simple circuit
Experiment 4
A bulb is connected to the battery by means of two connecting wires, two
pole terminals and a bulbholder. This experiment requires two wires approx.
25 cm in length, which have to be stripped off the insulation approx. 1 cm
at the ends. For cutting the wires an old pair of scissors will be sufficient.
Stripping the wire may be done with the fingernails, since the insulation
was chosen specially soft.
Materials:
1
1
1
2
1
1
Battery (18)
Spool of copper wire with red plastic insulation (31)
Bulbholder (33)
Terminal clips (27)
Screwdriver (24)
Bulb (1)
Fig. 3
2.2.2 Series circuit
Experiment 5
If two or more bulbs are connected to form a circuit, as shown in the illus­
tration, the result is a series circuit (connecting in series). The lamps will
light up darker, than one lamp alone. If one of the lamps is unscrewed in its
holder the other one will also go out.
Materials:
1
1
2
2
1
2
Battery (18)
Spool of copper wire with red plastic insulation (31)
Bulbholders (33)
Terminal clips (27)
Screwdriver (24)
Bulbs (1)
Fig. 4
2.2.3 Parallel circuit
Experiment 6
Two bulbs may also be connected to a battery as shown in the illustration.
In this instance the lamps are connected in parallel with each other. They
light up brightly. If one bulb is unscrewed in the bulbholder, the other one
continues to burn.
Materials:
1
1
2
2
1
2
Battery (18)
Spool of copper wire with red plastic insulation (31)
Bulbholders (33)
Terminal clips (27)
Screwdriver (24)
Bulbs (1)
Fig. 5
8
Electric Circuits
2.2.4 The switch in the circuit
Experiment 7
Electrical appliances will only operate if the circuit is closed. For closing
and opening circuits, switches are used. Battery, switch and bulb in its
holder are joined with connecting wires as shown in the illustration. When
closing the switch, the lamp lights up, when opening the switch it goes
out. – A lever switch is used for the experiment, because its functioning
can be observed well.
Materials:
1
1
1
2
1
1
1
Battery (18)
Spool of copper wire with red plastic insulation (31)
Bulbholder (33)
Terminal clips (27)
Screwdriver (24)
Bulb (1)
Lever switch (32)
Fig. 6
2.2.5 Building our own switch
Experiment 8
Lay the wooden board on the table and use it as base. Battery, bulbholder
and bulb are joined with connecting wires as shown in the illustration.
Connect a paper clip to the one wire coming from the end of the battery
(the other wire’s end is connected to the bulbholder). Do not forget to
strip off the insulation of the wire before connecting it. Paste the connected paper clip with the adhesive bonding compound BluTack upon
the wooden board.
Bend a second paper clip in such a way that it fulfills the function of a
spring, connect it to the wire coming from the bulbholder and fix it with
a pin vis-à-vis the first paper clip. The two clips together form the switch.
By pushing the “spring” upon the first paper clip the circuit is closed and
the lamp lights up (push-button switch).
Materials: 1
3
1
2
1
1
1
battery (18)
Spool of copper wire with red plastic insulation (31)
Bulbholder (33)
Terminal clips (27)
Screwdriver (24)
Bulb (1)
Wooden board (23)
Pins (20)
Paper clips (21)
Adhesive bonding compound BluTack (19)
Fig. 7
9
Electric Circuits
2.2.6 Assembling a vehicle with two headlights
Experiment 9
To assemble the demonstration vehicle with the two headlights, you need
the following materials:
1 Battery (18)
2–4 Spools of copper wire with red plastic insulation (31)
1–2 Bulbholders (33)
2 Terminal clips (27)
1 Screwdriver (24)
1–2 Bulbs (1)
1 Vehicle construction
set of fischertechnik components (25)
1 Rubber band (from the construction set)
Adhesive bonding compound BluTack (19)
Assembling of the vehicle
Fig. 8
The Kit “Electrical Circuits” contains a vehicle construction set of fischertechnik components. The base plate is used for the assembling of the vehicle
as shown below.
Two bulbholders are pasted on the base plate (using the adhesive bonding compound BluTack) and then connected to the battery by means of
connecting 4 wires and 2 terminal clips. The battery itself is attached on
the base plate by a rubber band.
10
Electric Circuits
Now try to screw in the light bulbs, and you will see – your vehicle has
got two headlights.
Note: You can also bring the two bulbs to light, using only three wires.
Remember the series circuit (see experiment 5) and connect the two bulbholders with each other.
Another arrangement could be to equip your vehicle with only one bulbholder, using 2 wires for connection. Paste the bulbholder on the top of
the drivers cab and screw in the light bulb.
Battery, attached by a rubber band
Variations of the electrical arrangement
Bulbholders, fixed with BluTack
Fig. 9
Fig. 10
2.2.7 The headlight-test
Experiment 10
You can use the headlight-test to proof the functioning of your vehicle
headlights. The headlights must remain flicker free even when the vehicle
is driving over a ground wave or crashing into a cardboard box. Assemble
a vehicle with two headlights and fulfil the test as shown in the picture
below.
Materials: as mentioned under experiment 9
Fig. 11
11
Electric Circuits
2.2.8 Trembling through a rollercoaster
Experiment 11
Build a copper wire rollercoaster on which you can test your dexterity.
1. Lay the grey plastic base on the table and insert the two crocodile clips
with their plug-ends into the terminals of the plastic base.
2. Bend the supple copper wire (430 mm length) into a rollercoaster and
connect its ends to the crocodile clips
3. Connect one crocodile clip to one end of the bulbholder, using the
insulated copper wire.
Fig. 12
4. The other end of the bulbholder is connected to the battery
5. Loop one end of the half-hard copper wire (200 mm length) but leave
a little opening to introduce the loop into the copper wire rollercoaster.
Connect the other end of the loopstick to the battery, using terminal
clips and the insulated copper wire.
Now test your electrical cleverness by introducing the loop into one end of
the copper wire rollercoaster (held by the two crocodile clips). Try to pass
the distance between the two clips without touching the wire. If the loop
touches the wire, the circuit will be closed and the lamp will light up.
Materials:
1
3
1
3
1
1
1
1
1
2
Battery (18)
Spools of copper wire with red plastic insulation (31)
Bulbholder (33)
Terminal clips (27)
Screwdriver (24)
Bulb (1)
Plastic base, grey (22)
Copper wire, supple, 1.5 mm dia., 430 mm long (15)
Copper wire, half-hard, 2 mm dia., 200 mm long (16)
Crocodile clips with plugs (30)
Fig. 13
2.3 Conductivity of materials
2.3.1 Which materials conduct the electrical current?
Experiment 12
An open circuit with light bulb, battery and three connecting wires is set
up. The gap in the circuit is bridged alternatively with the small materials
shown in the illustrations.
The metals (copper, aluminium, brass, iron) and carbon conduct the electric current whereas stone, rubber, dry wood, porcelain, glass, plastics etc.
do not; they are insulators.
Materials:
12
1
1
1
2
1
1
1
Battery (18)
Spool of copper wire with red plastic insulation (31)
Bulbholder (33)
Terminal clips (27)
Screwdriver (24)
Bulb (1)
Set of small materials (3,4-14)
Fig. 14
Fig. 15
Electric Circuits
2.4.Danger through electric current
2.4.1 Electric current from the socket
Experiment 13
To come in contact with electric current from the socket is extremely
dangerous. Beside you find some pictures which show situations that can
endanger your life.
Where have you already seen something similar? Ask adults after accidents
with electric current. Discuss in class.
Fig. 16
2.4.2 Caution! High voltage!
Experiment 14
Fig. 17
Wherever you see this sign you have to strictly keep away. The signs are
not everywhere therefore keep in mind that it is dangerous to touch any
conductors which are connected to the power supply system.
Where have you already seen the sign?
2.5.Electric current generates heat
2.5.1 Electric current generates heat
Fig. 18
Experiment 15
Connect heating wire (length approx. 80 cm) to the battery and to the
lever switch. Make connection between lever switch and battery by means
of copper wire with red insulation. Wind heating wire into a coil (by wrapping it around a pencil). Close the circuit by pushing down the lever of
the lever switch. A heating effect can be felt by touching the heating wire
with the fingertips.
In order to measure the heat generation, wind the heating wire coil carefully round the thermometer bulb. When the circuit is closed, the generation will be noticeable on the thermometer.
Note: Please check the battery’s power before you start with the experiment. The battery can be worn out because of its use in previous experiments.
Materials:
1
1
1
1
2
1
1
Spool of heating wire with grey cotton insulation (29)
Battery (18)
Spool of copper wire with red plastic insulation (31)
Thermometer (17)
Terminal clips (27)
Screwdriver (24)
Lever switch (32)
Fig. 19
13
Electric Circuits
2.6 Electric current sets in motion
2.6.1 The electromagnet
Experiment 16
An iron coil which is wrapped around by a wire is an electromagnet. The large nail is wound with enamelled wire (length
approx. ­1 m) after transparent enamel has been scraped off the ends. A
connection to the battery and the lever switch is made. The connection
between lever switch and battery is made by means of connecting wire
(red insulation). Close the circuit with the lever switch and the large nail
will get magnetized. Then position the small nail as shown. It is attracted
by the large nail which functions as an electromagnet when the current
passes through.
Materials: 1
1
1
2
1
1
1
1
Spool of copper wire with transparent enamel
insulation (30)
Battery (18)
Spool of copper wire with red plastic insulation (31)
Terminal clips (27)
Screwdriver (24)
Lever switch (32)
Large nail (26)
Small nail (6)
Fig. 20
3 Underlying principles
Generation of Current
Electric current is mainly generated by means of generators or galvanic
elements. Generators utilize electromagnetic phenomena for the purpose
of converting mechanical energy into electrical energy. The generators in
power stations are driven either by steam power (thermal power stations,
also atomic power stations) or by water power by means of turbines. Galvanic elements (batteries) convert chemical energy into electrical energy.
Basic components of a galvanic element are: a zinc can (negative electrode)
containing a carbon rod (positive electrode). Inside the zinc container
there is a mixture of water, magnesium dioxide, ammonium chloride and
sawdust. The ammonium chloride serves as the electrolyte. Inside a 4,5
Volt flash lamp battery (square battery) there are three series-connected
elements. (See picture below.)
Square battery
14
Galvanic element
Fig. 21
Electric Circuits
Process in the Circuit
If the two poles of a current source, e.g. of a battery, are conductively
connected, then electrons flow from the negative pole through the line
to the positive pole. This is called a closed circuit. An electrical appliance
included in this flow of electrons converts the electrical energy, according
to its construction, into another form of energy e.g. light.
For the assembly of an electric circuit, connecting wires, a bulbholder and
terminal clips can be employed. A circuit can be conveniently opened or
closed by means of a switch.
Electrical Connections
Fig. 22
There are two ways of connecting several electrical appliances to a current
source: the series connection (connecting in series) and the parallel connection. In the case of the series connection both bulbs light up darker
than with the parallel connection, because their individual resistances add
up, so that the current drops correspondingly. If in a series connection
one of e.g. two bulbs is unscrewed in its holder, then the other bulb also
goes out.
In the case of the parallel connection, however, each lamp is in an individual
circuit. For this reason one of the two lamps can be unscrewed without
the other going out.
Series connection
Fig. 23
Conductors and non-conductors
Materials which conduct the electric current are conductors, those that
do not are non-conductors. Silver conducts very well, equally copper.
Nichrome and constantan on the other hand are poorer conductors, they
possess a high resistance. The non-conductors (insulators) comprise plastics, dry wood, rubber, porcelain, glass, etc.
Filaments in bulbs generally consist of the hard-to-melt metal tungsten
(melting point: 3350 °C). To prevent the filament from being burnt, the
glass of bulbs from 40 watts upward is filled with an inert gas (argon,
krypton). The surface area of the filament effecting the undesirable heat
dissipation is reduced by coiling the filament once or twice. A defective
glass makes a bulb unserviceable, since the filament immediately burns
when exposed to the air if current is flowing through it.
Parallel connection
Fig. 24
High-conductivity copper wire is generally used for power supply cables;
those parts of an appliance serving the generation of heat, however, are
provided with a resistance wire.
Electromagnetism
A magnetic field originates around a wire through which current flows,
which can be increased by winding the wire into a coil. If an iron core
is added, the magnetic force is concentrated still further; the result is an
electromagnet which is effective as long as current flows through the wire.
Most electrical appliances which generate a motion including the electric
motor operate on this principle.
4.Important information
Electric current can be dangerous. Experiments with electric current from
a torch are not dangerous. However, experiments with electric current
from the socket and any touching of conductors which are connected to
the power supply system are life threatening.
15
Experiment Description/Manual Science Kit “Electric Circuits”
Order no. 31772 6
Holzhauser Straße 76
13509 Berlin/Germany
© 2009 Cornelsen Experimenta, Berlin Tel.: +49 30 435 902-0
Fax: +49 30 435 902-22
eMail: [email protected]
Internet: www.corex.de
08.00