An intermediate LED circuit explained in detail.
Current flows from the positive to the negative.
Electrons flow from the negative to the positive.
The resistor must always go on the negative before it reaches the battery.
Battery chosen was a 9V battery as that battery voltage must be more than the calculated diode forward voltage. This is supplied with the LED when purchased. Can normally be around 2V for each LED. 3 x LED's @ 2V = 6V. So a 9V battery was chosen as its higher than the total calculated diode forward voltage.
LED current is 20ma for a Red or Orange LED.
Battery Voltage minus the calculated diode forward voltage of the LED's equals 7V.
9V - 2V = 7V
Voltage divided by LED current of 20ma equals total resistor value of 350ma.
7V / 20ma = 350ma
This has calculated the resistor size of 350ma. So choose the next higher available resistor value of 360ma.
