This app is intended to test the state of the LED in a simple circuit with resistors and battery.
Four types of battery supported: 1.5V, 3V,6V and 9V.
Implemented with simple drag and drop function so that anyone can use this app.
Cost of electric components( battery, resistors and LEDs ) can be reduced. It is also useful in preventing accidental damages like the explosion of LED due to high voltage supply.