Capacitors

Electronics is a fascinating subject to most kids. Turning on a LED bulb, making a simple circuit will make them dive into much more interesting areas in the field of electronics. PSLab android application with the help of PSLab device implements a set of experiments whose target audience is school children. To make them more interested in science and electronics, there are several experiments implemented such as measuring body resistance, lemon cell experiment etc. This blog post brings out the basics in implementing these type of experiments and pre-requisite. Lemon Cell Experiment Lemon Cell experiment is a basic experiment which will make school kids interested in science experiments. The setup requires a fresh lemon and a pair of nails which is used to drive into the lemon as illustrated in the figure. The implementation in PSLab android application uses it’s Channel 1. The cell generates a low voltage which can be detected using the CH1 pin of PSLab device and it is sampled at a rate of 10 to read an accurate result. float voltage = (float) scienceLab.getVoltage("CH1", 10); 2000 instances are recorded using this method and plotted against each instance. The output graph will show a decaying graph of voltage measured between the nails driven into the lemon. for (int i = 0; i < timeAxis.size(); i++) { temp.add(new Entry(timeAxis.get(i), voltageAxis.get(i))); } Human Body Resistance Measurement Experiment This experiment attracts most of the young people to do electronic experiments. This is implemented in the PSLab android application using Channel 3 and the Programmable Voltage Source 3 which can generate voltage up to 3.3V. The experiment requires a human with drippy palms so it makes a good conductance between device connection and the body itself. The PSLab device has an internal resistance of 1M Ohms connected with the Channel 3 pin. Experiment requires a student to hold two wires with the metal core exposed; in both hands. One wire is connected to PV3 pin when the other wire is connected to CH3 pin. When a low voltage is supplied from the PV3 pin, due to heavy resistance in body and the PSLab device, a small current in the range of nano amperes will flow through body. Using the reading from CH3 pin and the following calculation, body resistance can be measured. voltage = (float) scienceLab.getVoltage("CH3", 100); current = voltage / M; resistance = (M * (PV3Voltage - voltage)) / voltage; This operation is executed inside a while loop to provide user with a continuous set of readings. Using Java threads there is a workaround to implement the functionalities inside the while loop without overwhelming the system. First step is to create a object without any attribute. private final Object lock = new Object(); Java threads use synchronized methods where other threads won’t start until the first thread is completed or paused operation. We make use of that technique to provide enough time to read CH3 pin and display output. while (true) { new MeasureResistance().execute(); synchronized (lock) { try { lock.wait();…