An electric iron marked "220v45w", how much heat is produced per minute at rated voltage?
According to the heat formula, it should be correct.
The electric power of electric iron can be regarded as heating power basically, electric energy is transformed into heat energy, efficiency is very high. Then, with the power of 45W heating, the heat generated in 1 minutes is Q=Pt=45 * 60=2700JThe electric iron is pure resistive load, the power factor is 1, so I=P/U=45 / 220 = 0.205A
Q＝W＝Pt = 45W×1分= 45W×60＝2700j
