I'm using 0.2 W, 500 Ω potentiometer with 300mA safely (there is no heat or abnormal behavior). But according to calculation, max current of this potentiometer is about 20mA. Is my calculation wrong?
$$P = VI = I^2 R$$ $$0.2W = I^2 500 \Omega$$ $$I = \sqrt{\frac{0.2W}{500\Omega}} = 0.02A$$
Edit:
I'm confused about power rating of potentiometer. It's max value is 500 Ω and power rating is 0.2 W, so max current is 20 mA. But when I use only part of the potentiometer, 20 mA limit can be applied? I'm using 3 Ω part with 300 mA.
Edit:
Entire circuit is like this:
simulate this circuit – Schematic created using CircuitLab
There are 40 set of R - LED - LED totally. The current of each set is about 7 mA. (I measured voltage across the 100 Ω resistors and it's 0.7 V) And I measured current between P1 and 40 (R - LED - LED) s and it was about 280 mA. I used pot for brightness control.
Edit:
I used only 2 part of the pot. Is this not recommended? Why? (I'm just hobbyist and forgive me if this is too basic question)
This is test video: https://www.youtube.com/watch?v=Su1ZFqXYfIE The voltage seen on the multimeter is the voltage across a 100 Ω resistor, as shown on the circuit diagram.