## Posts

### Capacitors: Calculations & Simulations on Charging, Discharging Time & Voltage

Assume charging a completely discharged capacitor, under resistance, R with an applied potential, E having the capacitance, C. Potential across the capacitor is E c . At time, t = 0s or t o :   E C < E; E C = 0 V. If it is fully charged then E C = E and t = t c . ‘E’ is the maximum potential attained by the capacitor. Time to reach maximum potential is: (t c – t o ).   At any given time, ‘t’ on charging in between t o and t c the potential of the capacitor, E C is related to the maximum potential, E by the relation, where ‘t’ is the elapsed time during charging ‘R’ is the resistance in Î© ‘C’ is the capacitance in F.   The product of R and C is called the time constant and is represented as, Ï„. So, Ï„ = R × C.   Unit for Ï„ Ï„ = R × C = Î© × {F} = Î© × {C × V –1 } C = Charge in Coulombs = A × s = Î© × {A × s × V –1 } = = Î© × {V × Î© –1 × s × V –1 } = s. At one time constant, capacitor is 63.2% charged. I

### Full Width at Half Maximum (FWHM) & Quadratic equation

Full width at half maximum (FWHM) for a curve is used in many scientific experimental data analyses. For instance, in X–ray diffraction analysis of crystal data, it is used to find the grain size from the curve. FWHM is the width of the curve or simply the difference in the corresponding two ‘x’ data values at y max /2. y max refers the highest value of ‘y’ or ‘y’ value for the maximum peak height.   Example Set of ‘x’ and ‘y’ data and the corresponding curve is given below: (View this Page for back reference.)     x      y 0.0    0.000 0.1    0.146 0.2    0.284 0.3    0.414 0.4    0.536 0.5    0.650 0.6    0.756 0.7    0.854 0.8    0.944 0.9    1.026 1.0    1.100 1.1    1.166 1.2    1.224 1.3    1.274 1.4    1.316 1.5    1.350 1.6    1.376 1.7    1.394 1.8    1.404 1.9    1.406 2.0    1.400 2.1    1.386 2.2    1.364 2.3    1.334 2.4    1.296 2.5    1.250 2.6    1.196 2.7    1.134 2.8    1.064 2.9

### Specific Capacitance of a Supercapacitor from Cyclic Voltammetry data

Formula   C s - Specific capacitance (F/g) = to be calculated. A - Area under the I vs. E curve (AV) = 0.0154 m - Mass of the electrode material (g) = 20 mg = 0.02 g Î½ - Scan rate (V/s) = 10 mV/s = 0.01 V/s dV - Potential window (difference in potential) = 0.3 (= 0.0 V (-0.3 V))   Area (A) under the curve can be calculated using Origin program , whereas 'dV' is the difference in the potential. Refer the video tutorial for the calculations of 'A' and 'dV'. https://youtu.be/AzfnyTgADh0   By, Dr. M Kanagasabapathy Associate Professor Department of Chemistry Rajapalayam Rajus College Madurai Kamaraj University Rajapalayam 626117 (TN)

### Logical Thinking Puzzles

Blue Fishes There are 200 fishes in a pond. 99% fishes are blue. How many blue fishes should be removed to make the percentage of blue fishes in to 98%? Hint: 2 is not the answer. Answer First, why '2' is not the right answer? If you think 198 is the initial number of blue fishes and if 2 blue fishes are removed, then there will be 196 blue fishes and hence in terms of percentage it is 98. But its wrong, since the total fishes count also decreased to 198, if you just remove 2 blue fishes alone. So the percentage of blue fishes are (196/198) × 100 = 98.99% Its not 98% its almost 99%. In simple, 198 blue fishes and 2 other colored fishes are there initially. And if you remove 100 blue fishes, then 98 blue fishes with 2 other colored fishes. So, the percentage of blue fishes becomes 98. Answer: 100 blue fishes should be removed. Show the Answer Tennis Match Antony and Benjamin played tennis against each other. Its a bet game and

### Stock Option Chain Data in Excel Sheet

Simplified Excel sheet for Stock Option traders to fetch and analyze NSE Stock Option Chain Data for both Calls and Puts. This Excel sheet fetches the live NSE Stock Option Chain data such as OI and Price at different strike prices specifically few Strike Price ranges near to ATM in Excel sheet.               This is coded in VBA and can fetch the following data at a given Strike Price, for both Calls (CE) and Puts (PE) and at different Expiry Dates. > Open Interest (OI) > Change in Open Interest (in %), > Last Traded Price for NSE Stock option (in INR) > Change in Last Traded Price (%)   It narrows down and fetches few selective Strike Price ranges only at Out of Money (OTM) near to ATM (At the Money) and not fetches from deep far Out of Money Strike Price data. So, it gives a simplified view on OI and Price changes.   How to use? 1. Select the Stock Symbol. 2. Then Select the Expiry Date an

### VESTA Tutorial: Simulation of XRD patterns – Matrix transformation of {h k l} planes Miller indices

This VESTA tutorial demonstrates the following: 1. How to download and analyze .cif (Crystallographic Information File) from Open Crystallographic Database using VESTA program? 2. How to simulate X-ray diffraction patterns in VESTA from the crystal unit cell volume? 3. How to interpret and view the lattice planes, d-spacing in a 3-dimensional way? 4. How to perform matrix transformation correctly, in {hkl} Miller indices planes? 5. Matrix transformation by using simple matrix multiplication followed by the location of the new Miller plane after the transformation.   6. Identification of Miller {hkl} planes from crystal dimensions and XRD patterns. 7. Correlates the unit cell dimensions, d-spacing and 2-theta (2Î¸) values.

### Python code to Laptop Battery Life Saver - Battery Status Check

Coded a light-weight Python program (600 KB), 'Battery Life Saver' to extend the life span of laptop batteries with GUI (Graphical User Interfae)   Using a Laptop Battery continuously by overcharging above 90% or by below 15%, reduces its life span.   This light-weight .exe program, Battery Life Saver will alarm, on excess charging or discharging.     Check this page for downloading this program Download Battery Life Saver Program     Battery percentage can be checked by ‘psutil’ and it can retrieve battery information. psutil (process and system utilities) is a cross-platform library for retrieving information on running processes and system utilization (CPU, memory, disks, network, sensors) in Python.   Installation of psutil Windows in Command Prompt as Administrator:   pip install psutil   For Linux distributions: sudo apt-get install gcc python3-dev sudo pip3 install psutil   Code   import psutil   # Get

### Automating References or Bibliography for Research Paper, Book, PhD Thesis

Zotero Tutorial - Automating References / Bibliography for Writing Research Paper, Book and PhD Thesis in MS Word. For academicians, researchers and Ph.D. scholars, inserting & editing the References or  Bibliography manually to a specific Journal Reference style is tedious & time consuming, while writing a research paper or a book or a PhD thesis or manuscripts with MS Word processor. With Zotero (freeware) in Word this boring and cumbersome referencing  process can be automated easily and quickly. This video tutorial demonstrates how to insert / modify the references fetched from webpages in word using Zotero.

### Rietveld refinement of crystal data by FullProf suite computer program

This video tutorial demonstrates the first basics of the Rietveld refinement using FullProf Suite computer program (freeware), for crystal structures based on crystallographic information file (.cif) and simulations for X-ray diffraction patterns.   YouTube Link: https://www.youtube.com/watch?v=1lMi_uI9R58   By, Dr. M Kanagasabapathy Assistant Professor Department of Chemistry Rajapalayam Rajus’ College Madurai Kamaraj University Rajapalayam (TN) India

### Electronic Circuit Simulator - Free tool to analyze electronic circuits

Free electronic circuit simulator to study and analyze electronic circuits. It has a good user interface and has a sizable number of circuit components. Its very useful tool for educational purposes and to analyze basic circuits to complicated circuits. Download Links  Windows       Linux   Mac (If not downloaded, o pen the link in New tab and enter.)

### Energy correlation between Pizza and Diesel

Assume a slice of pizza weighing 100 g has 250 Calories. Correlate its energy content to diesel (calorific value of diesel is 44000 kJ/kg; density of diesel is 0.83 kg L –1 ).   One dietary Calorie, C is equal to 1 kilocalories (kcal).   1 calorie = 4.184 Joules. 1 kg or 1000 g diesel has 44000 kJ = 44000/4.184 ≈ 10516 kcal.   In other words, 10516 kcal are present in 1000 g of diesel.   It is mentioned that, 100 g pizza = 250 kcal (or 250 C). Therefore, 250 kcal are present in (250×1000)/ 10516 = 23.8 g diesel.   Density of diesel = 0.83 kg L –1 = 830 g per 1000 mL.   This means, 830 g diesel occupies 1000 mL volume.    ∴ 23.8 g diesel = (23.8×1000)/830 ≈ 28.7 mL.   Hence, 100 g pizza with 250 Calories ≅ 28.7 mL of diesel.