Lab on the lap
CELEBRATED English philosopher George Henry Lewes once said that science is the “systematic classification of experience”. Students gain scientific experience through experiments. But not all get the chance to conduct experiments. Due to funds crunch, many schools in the country, particularly those in the interior areas, cannot afford scientific experiments. For instance, an oscilloscope is a basic tool required for teaching electrical concepts, but it costs upwards of Rs 15,000. Most schools can only dream of such devices.
To fill this gap, a team led by Ajith Kumar, nuclear physicist at the Inter University Accelarator Centre (IUAC), Delhi, has developed a kit that can help perform about 100 physics experiments, from senior secondary to under-graduate levels. It costs just Rs 3,000. All it needs is a personal computer.
“The advent of personal computers has opened a new path for learning science. Addition of some hardware to an ordinary computer can convert it into a science laboratory by performing fast measurements at good accuracy, enabling us to study a wide range of phenomena,” says Kumar. The kit, which Kumar has named EXPeyes, is part of IUAC’s outreach programme, Phoenix or Physics with Home-made Equipment and Innovative Experiments.
The main device in EXPeyes kit is a light-weight 99 sq cm blue-box that can generate and measure varying voltages, just like an oscilloscope. The kit has several other accessories, such as resistor, capacitor, magnet, microphone and D C motor. A student can connect these devices to the terminals on the blue-box, depending on the experiment. The entire set-up can then be connected to the computer through a USB port. The blue-box provides both DC and AC current sources, whose voltage and frequency can be controlled through a software, freely downloaded from project website http://expeyes.in. The kit has a manual to get the experiments started. Kumar says EXPeyes opens up opportunities for teachers to demonstrate physical science to students in all its staggering beauty.
For example, if a teacher wants to demonstrate persistence of vision theory, he or she can connect EXPeyes to a light emitting diode (LED). Persistence of vision is a phenomenon by which the eye tends to retain an image for a fraction of a second. If another image is shown to the eye within this time, it creates a sense of continuity of vision, which is used in motion picture. For the experiment, the teacher can set the frequency of voltage of EXPeyes at 20 Hz. At this frequency, one can see the LED flickering. However, as we increase the frequency to about 50 Hz, the light becomes stable. This happens because at a frequency of 50 Hz, the LED flickers so fast that it appears stable.
Another experiment that first-year graduate students routinely do is to calculate resistance of a wire. Resistance is the property of material to oppose electric charge. Insulating materials like plastic have high resistance. To calculate resistance, all one needs to do is to connect the wire to EXPeyes. The software can easily calculate the resistance of the wire. It takes a student at least an hour to calculate the resistance using standard lab equipment like volt meter and ammeter.
P Arun, professor of electronics at Shri Guru Teg Bahadur Khalsa College, University of Delhi, says some faculty in his college are reluctant to accept EXPeyes because they say it makes experiments too simple. While it is important to know how to calculate resistance using standard lab equipment and graphs, it is pointless wasting time over it every time. EXPeyes prepares our students for professional and digital environment of research labs today. They can also perform the experiments beyond the lab hours, he says. Agrees V H Raybagkar, professor at Wadia College, University of Pune. “The device has piqued students’ curiosity in science.” Colleges under University of Pune, University of Calicut and Calcutta State University have integrated the device into their BSc syllabus. A school in France has also adopted EXPeyes for teaching physics.