Microcontrollers in Physics education: a circuit simulation ... - ICL

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Conference ICL2010 September 15 -17, 2010 Hasselt, Belgium specifications, the shape of the new device was defined. The most important of user requirements for the new device was to make a clear and obvious distinction between the light bulb and whatever was to be used to represent the free electrons. It was decided to use a familiar-to-students laboratory type incandescence lamp on the circuit, while SMD-type (Surface Mounted Device) LEDs (i.e. very small and flat Light Emitting Diodes) were used for the representation of the electrons. These 32 LEDS have been placed about 1cm apart in the surface of a circle and the space between them (that means the rest of the circle) has been painted red. This red line with the red LEDs embedded in it represents the cables of the circuit on the emulator board. The red colour was chosen on purpose, as it is the same with that of the cables used in the streaming video (presented during the lesson) that shows how to construct a simple electrical circuit with a light bulb. The use of this new device in class allows students an opportunity to experiment and observe the phenomena simulated, something that could not be performed in any other setup in any class or school laboratory 4 , while at the same time allowing some surreal perception as to the electron movement. Therefore, the new device may be proven to be of high educational value. It is also exciting enough to attract the student’s attention. It is more beneficial to the students if the use of the device is incorporated in a teaching sequence dealing with electric circuits, and electric current. To this purpose, during the trial, already existing material like the one previously prepared and residing at www.garyfallidou.org was used. A teaching sequence using this online material had already been developed and tested in class 3 . It was precisely that previous educational trial that revealed the necessity of a device that allows the visualisation of the electron movement. The already existing teaching sequence was, therefore, suitably modified to incorporate the new device. The device is safe and “easy-to-use” even by very young students and, although it is microcontroller driven, it does not require any computer knowledge. Nevertheless, when used in classroom, it would be better for the teacher to study carefully the online material and decide which parts he/she wishes to use. The new device is about the size of child’s notebook, and is lighter than a book (at least lighter than the majority of the books Greek students carry in their bags). ICL 2010 Proceedings – Page 411 2(12)
Conference ICL2010 September 15 -17, 2010 Hasselt, Belgium Picture 1. The new device consists of a microcontroller, 32 LEDs, a light bulb, a switch and an electricity sensor. An external source (either AC or DC) can be physically connected to this sensor, both to provide power and to get noticed by the students who handle it (Picture 1). A microcontroller is a small computer on a single integrated circuit (IC - chip) containing a processor core, memory, and programmable I/O peripherals. Some PROM memory is often included as well as a small amount of RAM. A microcontroller is a kind of miniature computer. Microcontrollers are used in many household electronic devices, as they are designed for embedded special purpose applications, in contrast to the microprocessors which are used for general purpose applications like in personal computers. The specific microcontroller used on the device has been programmed to sense 7 distinct cases: a) The presence of DC current clockwise and the switch in the “on” position b) The presence of DC current counterclockwise and the switch “on” c) The presence of DC current clockwise and the switch “off” d) The presence of DC current counterclockwise and the switch “off” e) The presence of AC current and the switch “on” f) The presence of AC current and the switch “off” g) The absence of electric potential (either from an empty battery or no existence of source). In this case, the position of the switch is indifferent because the circuit is open anyway, and the microcontroller drives the LEDs and the light bulbs accordingly. If the circuit is closed (as in the cases a, b, e) the microcontroller flashes the LEDs successively following the direction from the positive pole of the battery to the negative one and illuminates the light bulb. If the circuit is open (case c, d, f and g) the microcontroller flashes the LEDs randomly (to simulate random motion) and the light bulb does not illuminate. ICL 2010 Proceedings – Page 412 3(12)
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Microcontrollers in Physics education: a circuit simulation ... - ICL

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