First Name: Anastasios

Surname: Nezis

e-mail: nezis@mycosmos.gr

THE PUZZLE EXPERIMENT (PROJECT DESCRIPTIONS) The â&#x20AC;&#x153;Puzzle Experimentâ&#x20AC;? consists of 9 different experiments of electric current (electricity & electromagnetism) that can be presented one by one or as a whole. This can be possible because of the design of the bases (like puzzle pieces) and cables that connect (in parallel) all the experiments underneath. The 9 experiments have solenoids, compasses, magnets, motors & generators, resistances, variable resistances, lamps and electrolysis glasses. They show the basic uses of electric current in a 3 to 5 minute presentation. http://www.youtube.com/watch?v=6V0TLcDagsg

http://www.youtube.com/tasosne

1. THE RED PUZZLE: solenoid with 6 compasses around. When electric current flows through the solenoid, it becomes magnet and the compasses change their orientation, showing the magnetic field. Changing the polarity of the current, the compasses reverse their orientation, showing the reverse of the magnetic field.

2. THE YELLOW PUZZLE: solenoid with magnet in gallows. When electric current flows through the solenoid, it becomes a magnet and it attracts (or repels) the magnet. When we change the polarity of the current, the solenoid repels (or attracts) the magnet.

3. THE BLUE PUZZLE: motor & generator. A motor rotates when current flows through. When we transmit the rotation to another motor (with a rubber strap) it becomes a generator. Electric energy is converted to kinetic energy on the motor and kinetic energy is converted to electric on the generator. A small lamp conected to the generator lights.

4. THE BLACK-PURPLE PUZZLE: resistors (in series / parallel) & lamp. A lamp is connected to a resistor and glows. With a switch we put a second resistor in series and the lamp glows less. We go back to one resistor and with another switch we put another resistor in parallel to the first. The lamp now glows more. This shows the current dependence on the total resistance and the ways to connect resistors. (Accompanied by appropriate drawings).

5. THE PURPLE PUZZLE: simple and double rheostat. The simple rheostat increases gradually the resistance and switches off gradually the lamp. The double rheostat changes the current and as a result, the two lamps switch on and off successively. (Accompanied by appropriate drawings).

6. THE WHITE PUZZLE: motor and lamp. Motor (with fan) and lamp in series. When we turn off the switch, the motor is running but the light (though current goes through), it is not illuminated. When with our finger brake and stop the motor, the lamp is on. So we can see the conversion of electrical energy into kinetic and heat, or (in the 2nd case) just to heat.

7. THE BLACK PUZZLE: resistances with amperometer & voltmeter. Various combinations (1, 2 or 3 resistors) in series or parallel with indications of voltage (voltmeter) and current (ammeter). We can confirm Ohm's law and the ways of series and parallel connection. All resistors are identical, 10 ohms each. (Accompanied by appropriate drawings).

8. THE GREEN PUZZLE: coil inductance and mutual coupling. Part 1: solenoid and lamp. When the circuit carries current, the lamp is on. Then instantly we change the polarity of the current ( ± → m) and observe instantaneous increase of the brightness of the lamp, because of the energy of the magnetic field applied to the lamp. Part 2: Two square coils (A) and solenoid coil (B) with lamp. The two circuits (A: source with 2 coils & B: solenoid with lamp) are in inductive coupling. We make the "ON-OFF" switch blink quickly and the change in the magnetic field in the two coils-A alters the magnetic flux in solenoid -B and the inductive current lights the lamp. Alternatively we can connect AC power and light the lamp simply by pressing the switch (not by switching on and off). The change is achieved by the interchanging current. (Accompanied by appropriate drawings).

9. THE ORANGE PUZZLE: electrolysis. Three glasses with carbon electrodes (from AA) and lamps. The three sections are connected in parallel (common voltage) and the lights are the same. We put a) water, b) salt water and c) concentrated salt water and see the first lump off, the second glowing a little and the third glowing more. Alternatively, we can put HCl(aq), NaOH(aq) and NaCl(aq) or HCl(aq, 10%, 20%, 30%) to show the electrolytic properties of acids, bases and salts.

TECHNICAL DATA -The bases of these experiments are handmade from plywood 4 mm thick and painted with acrylic paints spray. They have dimensions 18 × 18 cm (imaginary square) with a radius of semicircles 4 cm (Accompanied by appropriate drawings). PUZZLE VOLTAGE -Materials (switches, cables, etc.) is trade. 1 RED 6 Volt (DC) -Hot silicone (hot glue) is used in the lower 2 YELLOW 6 Volt (DC) part of each experiment to fix the parts. 3 BLUE 10 Volt (DC) -The used voltages (via adapter) are: 4 BLACK8 Volt (DC) PURPLE 5 PURPLE 4 Volt (DC) 6 WHITE 6 Volt (DC) 7 BLACK 4 Volt (DC) 8 GREEN 9 Volt (DC), 6.3 Volt (AC) 9

ORANGE

7 Volt (DC)

PUZZLE EXPERIMENT

9 experiments of electric current

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