Sorry if I make mistakes, I am learning english. With the quarantin thing, I have started playin with electronics, but I realise I have no idea about the basics, so I read the articles about Ohm´s law and circuits( Vol. I - Direct Current (DC)) in that web. They are really good and explanatory!

I made an experiment, I have conected a 220 ohms and 3w resistor in an old laptop 19V power supply. My calculations were correct. 0,086 Amps. So, the disipate power must be 0,086x19 = 1,64 watts. But the resistor got very very hot in less than a minute. What is wrong? It is rated for 3 watts.

Thank you.

Best regards